diff --git a/.vscode/settings.json b/.vscode/settings.json
index 259a93eb..23cc1211 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -82,6 +82,7 @@
         "unflagged",
         "Unforwarded",
         "UNKEYWORD",
+        "Unselectable",
         "writeln",
         "xoauth"
     ],
diff --git a/README.md b/README.md
index 906c4ad7..99482166 100644
--- a/README.md
+++ b/README.md
@@ -314,6 +314,9 @@ The following SMTP extensions are supported:
 The following security extensions are supported:
 * ✅ Partial signing of messages using [DKIM](https://tools.ietf.org/html/rfc6376)
  
+### Other
+* ✅ [Mailto](https://tools.ietf.org/html/rfc6068) parsing mailto links
+* ✅ [Email provider auto-discovery](https://tools.ietf.org/html/rfc6186) Discover settings for an email address
 
 ### Supported encodings
 Character encodings:
diff --git a/analysis_options.yaml b/analysis_options.yaml
index f57ba05b..6eecbf36 100644
--- a/analysis_options.yaml
+++ b/analysis_options.yaml
@@ -4,6 +4,29 @@ analyzer:
     todo: ignore
   plugins:
     - dart_code_metrics # https://github.com/dart-code-checker/dart-code-metrics
+  exclude:
+    - '**/*.g.*'
+
+dart_code_metrics:
+  anti-patterns:
+    - long-method
+    - long-parameter-list
+  metrics:
+    cyclomatic-complexity: 20
+    maximum-nesting-level: 7
+    number-of-parameters: 10
+    source-lines-of-code: 100
+  metrics-exclude:
+    - test/**
+  rules:
+    - newline-before-return
+    - no-boolean-literal-compare
+    - no-empty-block
+    - prefer-trailing-comma
+    - prefer-conditional-expressions
+    - no-equal-then-else
+    - avoid-non-null-assertion
+
 linter:
   rules:
     - always_declare_return_types
@@ -148,15 +171,4 @@ linter:
     - use_to_and_as_if_applicable
     - valid_regexps
     - void_checks
-dart_code_metrics:
-  metrics:
-    # disable metrics
-    cyclomatic-complexity: 50
-    maximum-nesting-level: 50
-    number-of-parameters: 50
-    source-lines-of-code: 500
-    number-of-methods: 100
-  metrics-exclude:
-    - test/**
-  rules:
-    - avoid-non-null-assertion # comply to engineering standards and avoid !
+
diff --git a/example/discover.dart b/example/discover.dart
index dd660590..d1b618ac 100644
--- a/example/discover.dart
+++ b/example/discover.dart
@@ -18,8 +18,10 @@ void main(List<String> args) async {
     onlyPreferred = arguments.remove('--preferred');
     email = arguments.last;
     if (arguments.length != 1) {
-      email = args.firstWhere((arguments) => arguments.contains('@'),
-          orElse: () => '');
+      email = args.firstWhere(
+        (arguments) => arguments.contains('@'),
+        orElse: () => '',
+      );
       arguments.remove(email);
       print('Invalid arguments: $arguments');
       _usage();
@@ -38,7 +40,7 @@ void main(List<String> args) async {
     print('Unable to discover settings for $email');
   } else {
     print('Settings for $email:');
-    for (final provider in config.emailProviders!) {
+    for (final provider in config.emailProviders ?? []) {
       print('provider: ${provider.displayName}');
       print('provider-domains: ${provider.domains}');
       print('documentation-url: ${provider.documentationUrl}');
diff --git a/example/enough_mail_example.dart b/example/enough_mail_example.dart
index 0990b748..334dd6fe 100644
--- a/example/enough_mail_example.dart
+++ b/example/enough_mail_example.dart
@@ -33,7 +33,7 @@ Future<void> discoverExample() async {
     print('Unable to discover settings for $email');
   } else {
     print('Settings for $email:');
-    for (final provider in config.emailProviders!) {
+    for (final provider in config.emailProviders ?? []) {
       print('provider: ${provider.displayName}');
       print('provider-domains: ${provider.domains}');
       print('documentation-url: ${provider.documentationUrl}');
@@ -56,8 +56,9 @@ MimeMessage buildMessage() {
     ..from = [const MailAddress('Personal Name', 'sender@domain.com')]
     ..to = [
       const MailAddress('Recipient Personal Name', 'recipient@domain.com'),
-      const MailAddress('Other Recipient', 'other@domain.com')
+      const MailAddress('Other Recipient', 'other@domain.com'),
     ];
+
   return builder.buildMimeMessage();
 }
 
@@ -67,7 +68,7 @@ Future<MimeMessage> buildMessageWithAttachment() async {
     ..from = [const MailAddress('Personal Name', 'sender@domain.com')]
     ..to = [
       const MailAddress('Recipient Personal Name', 'recipient@domain.com'),
-      const MailAddress('Other Recipient', 'other@domain.com')
+      const MailAddress('Other Recipient', 'other@domain.com'),
     ]
     ..addMultipartAlternative(
       plainText: 'Hello world!',
@@ -75,6 +76,7 @@ Future<MimeMessage> buildMessageWithAttachment() async {
     );
   final file = File.fromUri(Uri.parse('file://./document.pdf'));
   await builder.addFile(file, MediaSubtype.applicationPdf.mediaType);
+
   return builder.buildMimeMessage();
 }
 
@@ -90,6 +92,7 @@ Future<void> mailExample() async {
     // and [MailAccount.fromManualSettingsWithAuth]
     // factory constructors for details.
     print('Unable to auto-discover settings for $email');
+
     return;
   }
   print('connecting to ${config.displayName}.');
@@ -127,15 +130,20 @@ Future<void> mailExample() async {
 Future<void> imapExample() async {
   final client = ImapClient(isLogEnabled: false);
   try {
-    await client.connectToServer(imapServerHost, imapServerPort,
-        isSecure: isImapServerSecure);
+    await client.connectToServer(
+      imapServerHost,
+      imapServerPort,
+      isSecure: isImapServerSecure,
+    );
     await client.login(userName, password);
     final mailboxes = await client.listMailboxes();
     print('mailboxes: $mailboxes');
     await client.selectInbox();
     // fetch 10 most recent messages:
     final fetchResult = await client.fetchRecentMessages(
-        messageCount: 10, criteria: 'BODY.PEEK[]');
+      messageCount: 10,
+      criteria: 'BODY.PEEK[]',
+    );
     fetchResult.messages.forEach(printMessage);
     await client.logout();
   } on ImapException catch (e) {
@@ -147,8 +155,11 @@ Future<void> imapExample() async {
 Future<void> smtpExample() async {
   final client = SmtpClient('enough.de', isLogEnabled: true);
   try {
-    await client.connectToServer(smtpServerHost, smtpServerPort,
-        isSecure: isSmtpServerSecure);
+    await client.connectToServer(
+      smtpServerHost,
+      smtpServerPort,
+      isSecure: isSmtpServerSecure,
+    );
     await client.ehlo();
     if (client.serverInfo.supportsAuth(AuthMechanism.plain)) {
       await client.authenticate('user.name', 'password', AuthMechanism.plain);
@@ -170,8 +181,11 @@ Future<void> smtpExample() async {
 Future<void> popExample() async {
   final client = PopClient(isLogEnabled: false);
   try {
-    await client.connectToServer(popServerHost, popServerPort,
-        isSecure: isPopServerSecure);
+    await client.connectToServer(
+      popServerHost,
+      popServerPort,
+      isSecure: isPopServerSecure,
+    );
     await client.login(userName, password);
     // alternative login:
     // await client.loginWithApop(userName, password);
diff --git a/lib/src/codecs/base64_mail_codec.dart b/lib/src/codecs/base64_mail_codec.dart
index 6ae56734..83fd676e 100644
--- a/lib/src/codecs/base64_mail_codec.dart
+++ b/lib/src/codecs/base64_mail_codec.dart
@@ -18,9 +18,13 @@ class Base64MailCodec extends MailCodec {
   /// [codec] the optional codec, defaults to utf8 [MailCodec.encodingUtf8].
   /// Set [wrap] to `false` in case you do not want to wrap lines.
   @override
-  String encodeText(String text,
-      {Codec codec = MailCodec.encodingUtf8, bool wrap = true}) {
+  String encodeText(
+    String text, {
+    Codec codec = MailCodec.encodingUtf8,
+    bool wrap = true,
+  }) {
     final charCodes = codec.encode(text);
+
     return encodeData(charCodes, wrap: wrap);
   }
 
@@ -32,8 +36,11 @@ class Base64MailCodec extends MailCodec {
   /// Set the [nameLength] for ensuring there is enough place for the
   /// name of the encoding.
   @override
-  String encodeHeader(String text,
-      {int nameLength = 0, bool fromStart = false}) {
+  String encodeHeader(
+    String text, {
+    int nameLength = 0,
+    bool fromStart = false,
+  }) {
     final runes = List.from(text.runes, growable: false);
     var numberOfRunesAbove7Bit = 0;
     var startIndex = -1;
@@ -105,6 +112,7 @@ class Base64MailCodec extends MailCodec {
       if (endIndex < text.length - 1) {
         buffer.write(text.substring(endIndex + 1));
       }
+
       return buffer.toString();
     }
   }
@@ -136,6 +144,7 @@ class Base64MailCodec extends MailCodec {
   @override
   String decodeText(String part, Encoding codec, {bool isHeader = false}) {
     final outputList = decodeData(part);
+
     return codec.decode(outputList);
   }
 
@@ -146,6 +155,7 @@ class Base64MailCodec extends MailCodec {
     if (wrap) {
       base64Text = _wrapText(base64Text);
     }
+
     return base64Text;
   }
 
@@ -171,6 +181,7 @@ class Base64MailCodec extends MailCodec {
       final startPos = chunkIndex * chunkLength;
       buffer.write(text.substring(startPos));
     }
+
     return buffer.toString();
   }
 }
diff --git a/lib/src/codecs/date_codec.dart b/lib/src/codecs/date_codec.dart
index c571de79..2351cd06 100644
--- a/lib/src/codecs/date_codec.dart
+++ b/lib/src/codecs/date_codec.dart
@@ -10,7 +10,7 @@ class DateCodec {
     'Thu',
     'Fri',
     'Sat',
-    'Sun'
+    'Sun',
   ];
   static const _months = <String>[
     'Jan',
@@ -24,7 +24,7 @@ class DateCodec {
     'Sep',
     'Oct',
     'Nov',
-    'Dec'
+    'Dec',
   ];
   static const _monthsByName = <String, int>{
     'jan': 1,
@@ -353,6 +353,7 @@ Date and time values occur in several header fields.  This section
       }
       buffer.write(minutes);
     }
+
     return buffer.toString();
   }
 
@@ -366,6 +367,7 @@ Date and time values occur in several header fields.  This section
       ..write('-')
       ..write(dateTime.year)
       ..write('"');
+
     return buffer.toString();
   }
 
@@ -474,31 +476,32 @@ Date and time values occur in several header fields.  This section
       if (reminder.length > spaceIndex) {
         reminder = reminder.substring(spaceIndex + 1).trim();
         spaceIndex = reminder.indexOf(' ');
-        if (spaceIndex == -1) {
-          zoneText = reminder;
-        } else {
-          zoneText = reminder.substring(0, spaceIndex);
-        }
+        zoneText =
+            spaceIndex == -1 ? reminder : reminder.substring(0, spaceIndex);
       }
     }
     final dayOfMonth = int.tryParse(dayText);
     if (dayOfMonth == null || dayOfMonth < 1 || dayOfMonth > 31) {
       print('Invalid day $dayText in date $dateText');
+
       return null;
     }
     final month = _monthsByName[monthText.toLowerCase()];
     if (month == null) {
       print('Invalid month $monthText in date $dateText');
+
       return null;
     }
     final year = int.tryParse(yearText.length == 2 ? '20$yearText' : yearText);
     if (year == null) {
       print('Invalid year $yearText in date $dateText');
+
       return null;
     }
     final timeParts = timeText.split(':');
     if (timeParts.length < 2) {
       print('Invalid time $timeText in date $dateText');
+
       return null;
     }
     int? second = 0;
@@ -509,6 +512,7 @@ Date and time values occur in several header fields.  This section
     }
     if (hour == null || minute == null || second == null) {
       print('Invalid time $timeText in date $dateText');
+
       return null;
     }
     if (zoneText.length != 5) {
@@ -528,17 +532,17 @@ Date and time values occur in several header fields.  This section
     final timeZoneMinutes = int.tryParse(zoneText.substring(3));
     if (timeZoneHours == null || timeZoneMinutes == null) {
       print('invalid time zone $zoneText in $dateText');
+
       return null;
     }
     var dateTime = DateTime.utc(year, month, dayOfMonth, hour, minute, second);
     final isWesternTimeZone = zoneText.startsWith('+');
     final timeZoneDuration =
         Duration(hours: timeZoneHours, minutes: timeZoneMinutes);
-    if (isWesternTimeZone) {
-      dateTime = dateTime.subtract(timeZoneDuration);
-    } else {
-      dateTime = dateTime.add(timeZoneDuration);
-    }
+    dateTime = isWesternTimeZone
+        ? dateTime.subtract(timeZoneDuration)
+        : dateTime.add(timeZoneDuration);
+
     return dateTime.toLocal();
   }
   // cSpell:enable
diff --git a/lib/src/codecs/mail_codec.dart b/lib/src/codecs/mail_codec.dart
index 8f47832e..4a6edc6f 100644
--- a/lib/src/codecs/mail_codec.dart
+++ b/lib/src/codecs/mail_codec.dart
@@ -34,7 +34,8 @@ abstract class MailCodec {
   /// Typical maximum length of a single text line
   static const String _encodingEndSequence = '?=';
   static final _headerEncodingExpression = RegExp(
-      r'\=\?.+?\?.+?\?.+?\?\='); // the question marks after plus make this regular expression non-greedy
+    r'\=\?.+?\?.+?\?.+?\?\=',
+  ); // the question marks after plus make this regular expression non-greedy
   static final _emptyHeaderEncodingExpression = RegExp(r'\=\?.+?\?.+?\?\?\=');
 
   /// UTF8 encoding
@@ -130,7 +131,7 @@ abstract class MailCodec {
     'base-64': base64.decodeText,
     '7bit': decodeOnlyCodec,
     '8bit': decodeOnlyCodec,
-    contentTransferEncodingNone: decodeOnlyCodec
+    contentTransferEncodingNone: decodeOnlyCodec,
   };
 
   static final _binaryDecodersByName = <String, Uint8List Function(String)>{
@@ -139,7 +140,7 @@ abstract class MailCodec {
     'base-64': base64.decodeData,
     'binary': decodeBinaryTextData,
     '8bit': decode8BitTextData,
-    contentTransferEncodingNone: decode8BitTextData
+    contentTransferEncodingNone: decode8BitTextData,
   };
 
   /// bas64 mail codec
@@ -153,15 +154,21 @@ abstract class MailCodec {
   /// [text] specifies the text to be encoded.
   /// [codec] the optional codec, which defaults to utf8.
   /// Set [wrap] to false in case you do not want to wrap lines.
-  String encodeText(String text,
-      {convert.Codec codec = encodingUtf8, bool wrap = true});
+  String encodeText(
+    String text, {
+    convert.Codec codec = encodingUtf8,
+    bool wrap = true,
+  });
 
   /// Encodes the header text in the chosen codec's only if required.
   ///
   /// [text] specifies the text to be encoded.
   /// Set the optional [fromStart] to true in case the encoding should
   /// start at the beginning of the text and not in the middle.
-  String encodeHeader(String text, {bool fromStart = false});
+  String encodeHeader(
+    String text, {
+    bool fromStart = false,
+  });
 
   /// Encodes the given [part] text.
   Uint8List decodeData(String part);
@@ -169,8 +176,11 @@ abstract class MailCodec {
   /// Decodes the given [part] text with the given [codec].
   ///
   /// [isHeader] is set to the `true` when this text originates from a header
-  String decodeText(String part, convert.Encoding codec,
-      {bool isHeader = false});
+  String decodeText(
+    String part,
+    convert.Encoding codec, {
+    bool isHeader = false,
+  });
 
   /// Decodes the given header [input] value.
   static String? decodeHeader(final String? input) {
@@ -189,7 +199,7 @@ abstract class MailCodec {
         containsEncodedWordsWithoutSpace) {
       final match = _headerEncodingExpression.firstMatch(cleaned);
       if (match != null) {
-        final sequence = match.group(0)!;
+        final sequence = match.group(0) ?? '';
         final separatorIndex = sequence.indexOf('?', 3);
         final endIndex = separatorIndex + 3;
         final startSequence = sequence.substring(0, endIndex);
@@ -222,6 +232,7 @@ abstract class MailCodec {
     }
     final buffer = StringBuffer();
     _decodeHeaderImpl(cleaned, buffer);
+
     return buffer.toString();
   }
 
@@ -229,7 +240,7 @@ abstract class MailCodec {
     RegExpMatch? match;
     var reminder = input;
     while ((match = _headerEncodingExpression.firstMatch(reminder)) != null) {
-      final sequence = match!.group(0)!;
+      final sequence = match?.group(0) ?? '';
       final separatorIndex = sequence.indexOf('?', 3);
       final characterEncodingName =
           sequence.substring('=?'.length, separatorIndex).toLowerCase();
@@ -241,23 +252,27 @@ abstract class MailCodec {
       if (codec == null) {
         print('Error: no encoding found for [$characterEncodingName].');
         buffer.write(reminder);
+
         return;
       }
       final decoder = _textDecodersByName[decoderName];
       if (decoder == null) {
         print('Error: no decoder found for [$decoderName].');
         buffer.write(reminder);
+
         return;
       }
-      if (match.start > 0) {
+      if (match != null && match.start > 0) {
         buffer.write(reminder.substring(0, match.start));
       }
       final contentStartIndex = separatorIndex + 3;
       final part = sequence.substring(
-          contentStartIndex, sequence.length - _encodingEndSequence.length);
+        contentStartIndex,
+        sequence.length - _encodingEndSequence.length,
+      );
       final decoded = decoder(part, codec, isHeader: true);
       buffer.write(decoded);
-      reminder = reminder.substring(match.end);
+      reminder = reminder.substring(match?.end ?? 0);
     }
     if (buffer.isEmpty &&
         reminder.startsWith('=?') &&
@@ -274,6 +289,7 @@ abstract class MailCodec {
       return HeaderEncoding.none;
     }
     final group = match.group(0);
+
     return group?.contains('?B?') ?? group?.contains('?b?') ?? false
         ? HeaderEncoding.B
         : HeaderEncoding.Q;
@@ -288,14 +304,19 @@ abstract class MailCodec {
     final decoder = _binaryDecodersByName[tEncoding.toLowerCase()];
     if (decoder == null) {
       print('Error: no binary decoder found for [$tEncoding].');
+
       return Uint8List.fromList(text.codeUnits);
     }
+
     return decoder(text);
   }
 
   /// Decodes the given [data]
-  static String decodeAsText(final Uint8List data,
-      final String? transferEncoding, final String? charset) {
+  static String decodeAsText(
+    final Uint8List data,
+    final String? transferEncoding,
+    final String? charset,
+  ) {
     if (transferEncoding == null && charset == null) {
       // this could be a) UTF-8 or b) UTF-16 most likely:
       final utf8Decoded = encodingUtf8.decode(data, allowMalformed: true);
@@ -305,6 +326,7 @@ abstract class MailCodec {
           return comparison;
         }
       }
+
       return utf8Decoded;
     }
     // there is actually just one interesting case:
@@ -322,31 +344,40 @@ abstract class MailCodec {
       final codec = _charsetCodecsByName[cs.toLowerCase()]?.call();
       if (codec == null) {
         print('Error: no encoding found for charset [$cs].');
+
         return encodingUtf8.decode(data, allowMalformed: true);
       }
       final decodedText = codec.decode(data);
+
       return decodedText;
     }
     final text = String.fromCharCodes(data);
+
     return decodeAnyText(text, transferEncoding, charset);
   }
 
   /// Decodes the given [text]
-  static String decodeAnyText(final String text, final String? transferEncoding,
-      final String? charset) {
+  static String decodeAnyText(
+    final String text,
+    final String? transferEncoding,
+    final String? charset,
+  ) {
     final transferEnc = transferEncoding ?? contentTransferEncodingNone;
     final decoder = _textDecodersByName[transferEnc.toLowerCase()];
     if (decoder == null) {
       print('Error: no decoder found for '
           'content-transfer-encoding [$transferEnc].');
+
       return text;
     }
     final cs = charset ?? 'utf8';
     final codec = _charsetCodecsByName[cs.toLowerCase()]?.call();
     if (codec == null) {
       print('Error: no encoding found for charset [$cs].');
+
       return text;
     }
+
     return decoder(text, codec, isHeader: false);
   }
 
@@ -359,8 +390,11 @@ abstract class MailCodec {
       Uint8List.fromList(part.replaceAll('\r\n', '').codeUnits);
 
   /// Is a noop
-  static String decodeOnlyCodec(String part, convert.Encoding codec,
-          {bool isHeader = false}) =>
+  static String decodeOnlyCodec(
+    String part,
+    convert.Encoding codec, {
+    bool isHeader = false,
+  }) =>
       part;
 
   /// Wraps the text so that it stays within email's 76 characters
@@ -421,6 +455,7 @@ abstract class MailCodec {
     if (currentLineStartIndex < text.length) {
       buffer.write(text.substring(currentLineStartIndex));
     }
+
     return buffer.toString();
   }
 }
diff --git a/lib/src/codecs/quoted_printable_mail_codec.dart b/lib/src/codecs/quoted_printable_mail_codec.dart
index 14298909..c3e93c61 100644
--- a/lib/src/codecs/quoted_printable_mail_codec.dart
+++ b/lib/src/codecs/quoted_printable_mail_codec.dart
@@ -18,8 +18,11 @@ class QuotedPrintableMailCodec extends MailCodec {
   /// [codec] the optional codec, which defaults to utf8.
   /// Set [wrap] to false in case you do not want to wrap lines.
   @override
-  String encodeText(final String text,
-      {Codec codec = MailCodec.encodingUtf8, bool wrap = true}) {
+  String encodeText(
+    final String text, {
+    Codec codec = MailCodec.encodingUtf8,
+    bool wrap = true,
+  }) {
     final buffer = StringBuffer();
     final runes = List.from(text.runes);
     final runeCount = runes.length;
@@ -53,6 +56,7 @@ class QuotedPrintableMailCodec extends MailCodec {
         lineCharacterCount = 0;
       }
     }
+
     return buffer.toString();
   }
 
@@ -66,8 +70,12 @@ class QuotedPrintableMailCodec extends MailCodec {
   /// Set the optional [fromStart] to true in case the encoding should  start
   /// at the beginning of the text and not in the middle.
   @override
-  String encodeHeader(final String text,
-      {int nameLength = 0, Codec codec = utf8, bool fromStart = false}) {
+  String encodeHeader(
+    final String text, {
+    int nameLength = 0,
+    Codec codec = utf8,
+    bool fromStart = false,
+  }) {
     final runes = List.from(text.runes, growable: false);
     var numberOfRunesAbove7Bit = 0;
     var startIndex = -1;
@@ -165,6 +173,7 @@ class QuotedPrintableMailCodec extends MailCodec {
           buffer.write(qpWordTail);
         }
       }
+
       return buffer.toString();
     }
   }
@@ -176,8 +185,11 @@ class QuotedPrintableMailCodec extends MailCodec {
   /// Set [isHeader] to true to decode header text using the Q-Encoding scheme,
   /// compare https://tools.ietf.org/html/rfc2047#section-4.2
   @override
-  String decodeText(final String part, final Encoding codec,
-      {bool isHeader = false}) {
+  String decodeText(
+    final String part,
+    final Encoding codec, {
+    bool isHeader = false,
+  }) {
     final buffer = StringBuffer();
     // remove all soft-breaks:
     final cleaned = part.replaceAll('=\r\n', '');
@@ -214,6 +226,7 @@ class QuotedPrintableMailCodec extends MailCodec {
         buffer.write(char);
       }
     }
+
     return buffer.toString();
   }
 
@@ -235,6 +248,7 @@ class QuotedPrintableMailCodec extends MailCodec {
       }
       buffer.write(paddedHexValue);
     }
+
     return buffer.length - lengthBefore;
   }
 
@@ -244,6 +258,7 @@ class QuotedPrintableMailCodec extends MailCodec {
   String _encodeQuotedPrintableChar(int rune, Codec codec) {
     final buffer = StringBuffer();
     _writeQuotedPrintable(rune, buffer, codec);
+
     return buffer.toString();
   }
 
diff --git a/lib/src/discover/client_config.dart b/lib/src/discover/client_config.dart
index 772d698c..e62dce82 100644
--- a/lib/src/discover/client_config.dart
+++ b/lib/src/discover/client_config.dart
@@ -14,11 +14,14 @@ class ClientConfig {
   List<ConfigEmailProvider>? emailProviders;
 
   /// Checks if the client configuration is not valid
-  bool get isNotValid =>
-      emailProviders == null ||
-      emailProviders!.isEmpty ||
-      emailProviders!.first.preferredIncomingServer == null ||
-      emailProviders!.first.preferredOutgoingServer == null;
+  bool get isNotValid {
+    final emailProviders = this.emailProviders;
+
+    return emailProviders == null ||
+        emailProviders.isEmpty ||
+        emailProviders.first.preferredIncomingServer == null ||
+        emailProviders.first.preferredOutgoingServer == null;
+  }
 
   /// Checks if the client configuration is valid
   bool get isValid => !isNotValid;
@@ -26,19 +29,19 @@ class ClientConfig {
   /// Adds the specified email [provider]
   void addEmailProvider(ConfigEmailProvider provider) {
     emailProviders ??= <ConfigEmailProvider>[];
-    emailProviders!.add(provider);
+    emailProviders?.add(provider);
   }
 
   /// Gets the preferred incoming mail server
   ServerConfig? get preferredIncomingServer => emailProviders?.isEmpty ?? true
       ? null
-      : emailProviders!.first.preferredIncomingServer;
+      : emailProviders?.first.preferredIncomingServer;
 
   /// The preferred incoming IMAP-compatible mail server
   ServerConfig? get preferredIncomingImapServer =>
       emailProviders?.isEmpty ?? true
           ? null
-          : emailProviders!.first.preferredIncomingImapServer;
+          : emailProviders?.first.preferredIncomingImapServer;
   set preferredIncomingImapServer(ServerConfig? server) {
     emailProviders?.first.preferredIncomingImapServer = server;
   }
@@ -47,7 +50,7 @@ class ClientConfig {
   ServerConfig? get preferredIncomingPopServer =>
       emailProviders?.isEmpty ?? true
           ? null
-          : emailProviders!.first.preferredIncomingPopServer;
+          : emailProviders?.first.preferredIncomingPopServer;
   set preferredIncomingPopServer(ServerConfig? server) {
     emailProviders?.first.preferredIncomingPopServer = server;
   }
@@ -55,7 +58,7 @@ class ClientConfig {
   /// The preferred outgoing mail server
   ServerConfig? get preferredOutgoingServer => emailProviders?.isEmpty ?? true
       ? null
-      : emailProviders!.first.preferredOutgoingServer;
+      : emailProviders?.first.preferredOutgoingServer;
   set preferredOutgoingServer(ServerConfig? server) {
     emailProviders?.first.preferredOutgoingServer = server;
   }
@@ -64,7 +67,7 @@ class ClientConfig {
   ServerConfig? get preferredOutgoingSmtpServer =>
       emailProviders?.isEmpty ?? true
           ? null
-          : emailProviders!.first.preferredOutgoingSmtpServer;
+          : emailProviders?.first.preferredOutgoingSmtpServer;
   set preferredOutgoingSmtpServer(ServerConfig? server) {
     emailProviders?.first.preferredOutgoingSmtpServer = server;
   }
@@ -131,13 +134,13 @@ class ConfigEmailProvider {
   /// Adds the domain with the [name] to the list of associated domains
   void addDomain(String name) {
     domains ??= <String>[];
-    domains!.add(name);
+    domains?.add(name);
   }
 
   /// Adds the incoming [server].
   void addIncomingServer(ServerConfig server) {
     incomingServers ??= <ServerConfig>[];
-    incomingServers!.add(server);
+    incomingServers?.add(server);
     preferredIncomingServer ??= server;
     if (server.type == ServerType.imap && preferredIncomingImapServer == null) {
       preferredIncomingImapServer = server;
@@ -150,7 +153,7 @@ class ConfigEmailProvider {
   /// Adds the outgoing [server].
   void addOutgoingServer(ServerConfig server) {
     outgoingServers ??= <ServerConfig>[];
-    outgoingServers!.add(server);
+    outgoingServers?.add(server);
     preferredOutgoingServer ??= server;
     if (server.type == ServerType.smtp && preferredOutgoingSmtpServer == null) {
       preferredOutgoingSmtpServer = server;
@@ -211,9 +214,11 @@ enum Authentication {
   secure,
 
   /// Family of authentication protocols
+  // cSpell: disable-next-line
   ntlm,
 
   /// Generic Security Services Application Program Interface
+  // cSpell: disable-next-line
   gsapi,
 
   /// The IP address of the client is used (very insecure)
@@ -407,6 +412,7 @@ class ServerConfig {
       default:
         text = 'UNKNOWN';
     }
+
     return text;
   }
 }
diff --git a/lib/src/discover/discover.dart b/lib/src/discover/discover.dart
index feeaa275..9669d7b2 100644
--- a/lib/src/discover/discover.dart
+++ b/lib/src/discover/discover.dart
@@ -53,6 +53,7 @@ class Discover {
         );
       }
     }
+
     return config;
   }
 
@@ -91,13 +92,19 @@ class Discover {
       final baseDomain =
           DiscoverHelper.getDomainFromEmail(partialAccount.email);
       final clientConfig = await DiscoverHelper.discoverFromConnections(
-          baseDomain, infos,
-          isLogEnabled: isLogEnabled);
+        baseDomain,
+        infos,
+        isLogEnabled: isLogEnabled,
+      );
       if (clientConfig == null) {
-        _log('Unable to discover remaining settings from $partialAccount',
-            isLogEnabled);
+        _log(
+          'Unable to discover remaining settings from $partialAccount',
+          isLogEnabled,
+        );
+
         return null;
       }
+
       return partialAccount.copyWith(
         incoming: partialAccount.incoming.copyWith(
           serverConfig: clientConfig.preferredIncomingServer,
@@ -107,63 +114,78 @@ class Discover {
         ),
       );
     }
+
     return null;
   }
 
   static Future<ClientConfig?> _discover(
-      String emailAddress, bool isLogEnabled) async {
+    String emailAddress,
+    bool isLogEnabled,
+  ) async {
     // [1] auto-discover from sub-domain,
     // compare: https://developer.mozilla.org/en-US/docs/Mozilla/Thunderbird/Autoconfiguration
     final emailDomain = DiscoverHelper.getDomainFromEmail(emailAddress);
     var config = await DiscoverHelper.discoverFromAutoConfigSubdomain(
-        emailAddress,
-        domain: emailDomain,
-        isLogEnabled: isLogEnabled);
+      emailAddress,
+      domain: emailDomain,
+      isLogEnabled: isLogEnabled,
+    );
     if (config == null) {
       final mxDomain = await DiscoverHelper.discoverMxDomain(emailDomain);
       _log('mxDomain for [$emailDomain] is [$mxDomain]', isLogEnabled);
       if (mxDomain != null && mxDomain != emailDomain) {
         config = await DiscoverHelper.discoverFromAutoConfigSubdomain(
-            emailAddress,
-            domain: mxDomain,
-            isLogEnabled: isLogEnabled);
+          emailAddress,
+          domain: mxDomain,
+          isLogEnabled: isLogEnabled,
+        );
       }
       //print('querying ISP DB for $mxDomain');
 
       // [5] auto-discover from Mozilla ISP DB:
       // https://developer.mozilla.org/en-US/docs/Mozilla/Thunderbird/Autoconfiguration
       final hasMxDomain = mxDomain != null && mxDomain != emailDomain;
-      config ??= await DiscoverHelper.discoverFromIspDb(emailDomain,
-          isLogEnabled: isLogEnabled);
+      config ??= await DiscoverHelper.discoverFromIspDb(
+        emailDomain,
+        isLogEnabled: isLogEnabled,
+      );
       if (hasMxDomain) {
-        config ??= await DiscoverHelper.discoverFromIspDb(mxDomain,
-            isLogEnabled: isLogEnabled);
+        config ??= await DiscoverHelper.discoverFromIspDb(
+          mxDomain,
+          isLogEnabled: isLogEnabled,
+        );
       }
 
       // try to guess incoming and outgoing server names based on the domain
       final domains = hasMxDomain ? [emailDomain, mxDomain] : [emailDomain];
-      config ??= await DiscoverHelper.discoverFromCommonDomains(domains,
-          isLogEnabled: isLogEnabled);
+      config ??= await DiscoverHelper.discoverFromCommonDomains(
+        domains,
+        isLogEnabled: isLogEnabled,
+      );
     }
     //print('got config $config for $mxDomain.');
+
     return _updateDisplayNames(config, emailDomain);
   }
 
   static ClientConfig? _updateDisplayNames(
-      ClientConfig? config, String mailDomain) {
+    ClientConfig? config,
+    String mailDomain,
+  ) {
     final emailProviders = config?.emailProviders;
     if (emailProviders != null && emailProviders.isNotEmpty) {
       for (final provider in emailProviders) {
         if (provider.displayName != null) {
           provider.displayName =
-              provider.displayName!.replaceFirst('%EMAILDOMAIN%', mailDomain);
+              provider.displayName?.replaceFirst('%EMAILDOMAIN%', mailDomain);
         }
         if (provider.displayShortName != null) {
-          provider.displayShortName = provider.displayShortName!
-              .replaceFirst('%EMAILDOMAIN%', mailDomain);
+          provider.displayShortName = provider.displayShortName
+              ?.replaceFirst('%EMAILDOMAIN%', mailDomain);
         }
       }
     }
+
     return config;
   }
 
diff --git a/lib/src/imap/id.dart b/lib/src/imap/id.dart
index 0b13e7a9..a9a6f184 100644
--- a/lib/src/imap/id.dart
+++ b/lib/src/imap/id.dart
@@ -83,7 +83,7 @@ class Id {
     'date',
     'command',
     'arguments',
-    'environment'
+    'environment',
   ];
 
   /// Creates an ID from the given [text]
@@ -91,13 +91,14 @@ class Id {
     if (text == 'NIL' || !text.startsWith('(')) {
       return null;
     }
-    final entries = ParserHelper.parseListEntries(text, 1, ')', ' ')!;
+    final entries = ParserHelper.parseListEntries(text, 1, ')', ' ') ?? [];
     final map = <String, String>{};
     for (var i = 0; i < entries.length - 1; i += 2) {
       final name = _stripQuotes(entries[i]).toLowerCase();
       final value = _stripQuotes(entries[i + 1]);
       map[name] = value;
     }
+
     return Id(
       name: map.remove('name'),
       version: map.remove('version'),
@@ -118,6 +119,7 @@ class Id {
     if (input.startsWith('"')) {
       return input.substring(1, input.length - 1);
     }
+
     return input;
   }
 
@@ -162,6 +164,7 @@ class Id {
       }
     }
     buffer.write(')');
+
     return buffer.toString();
   }
 }
diff --git a/lib/src/imap/imap_client.dart b/lib/src/imap/imap_client.dart
index 89069694..c18c422f 100644
--- a/lib/src/imap/imap_client.dart
+++ b/lib/src/imap/imap_client.dart
@@ -166,6 +166,7 @@ class ImapServerInfo {
         }
       }
     }
+
     return methods;
   }
 
@@ -185,7 +186,7 @@ enum StoreAction {
   remove,
 
   /// Replace the flags of the message with the specified ones.
-  replace
+  replace,
 }
 
 /// Options for querying status updates
@@ -208,7 +209,7 @@ enum StatusFlags {
   /// The highest mod-sequence value of all messages in the mailbox.
   ///
   /// Only available when the CONDSTORE or QRESYNC capability is supported.
-  highestModSequence
+  highestModSequence,
 }
 
 /// Low-level IMAP library.
@@ -307,7 +308,10 @@ class ImapClient extends ClientBase {
     final startIndex = serverGreeting.indexOf('[CAPABILITY ');
     if (startIndex != -1) {
       CapabilityParser.parseCapabilities(
-          serverGreeting, startIndex + '[CAPABILITY '.length, _serverInfo);
+        serverGreeting,
+        startIndex + '[CAPABILITY '.length,
+        _serverInfo,
+      );
     }
     if (_queue.isNotEmpty) {
       // this can happen when a connection was re-established,
@@ -344,6 +348,7 @@ class ImapClient extends ClientBase {
     final parser = CapabilityParser(serverInfo);
     final response = await sendCommand<List<Capability>>(cmd, parser);
     isLoggedIn = true;
+
     return response;
   }
 
@@ -368,6 +373,7 @@ class ImapClient extends ClientBase {
     final response =
         await sendCommand<List<Capability>>(cmd, CapabilityParser(serverInfo));
     isLoggedIn = true;
+
     return response;
   }
 
@@ -400,6 +406,7 @@ class ImapClient extends ClientBase {
     final response =
         await sendCommand<List<Capability>>(cmd, CapabilityParser(serverInfo));
     isLoggedIn = true;
+
     return response;
   }
 
@@ -413,6 +420,7 @@ class ImapClient extends ClientBase {
     final response = await sendCommand<String>(cmd, LogoutParser());
     isLoggedIn = false;
     _isInIdleMode = false;
+
     return response;
   }
 
@@ -430,9 +438,12 @@ class ImapClient extends ClientBase {
       responseTimeout: defaultResponseTimeout,
     );
     final response = await sendCommand<GenericImapResult>(
-        cmd, GenericParser(this, _selectedMailbox));
+      cmd,
+      GenericParser(this, _selectedMailbox),
+    );
     log('STARTTLS: upgrading socket to secure one...', initial: 'A');
     await upgradeToSslSocket();
+
     return response;
   }
 
@@ -447,6 +458,7 @@ class ImapClient extends ClientBase {
       writeTimeout: defaultWriteTimeout,
       responseTimeout: defaultResponseTimeout,
     );
+
     return sendCommand(cmd, IdParser());
   }
 
@@ -458,6 +470,7 @@ class ImapClient extends ClientBase {
       responseTimeout: defaultResponseTimeout,
     );
     final parser = CapabilityParser(serverInfo);
+
     return sendCommand<List<Capability>>(cmd, parser);
   }
 
@@ -520,8 +533,10 @@ class ImapClient extends ClientBase {
   }) {
     if (targetMailbox == null && targetMailboxPath == null) {
       throw InvalidArgumentException(
-          'move() error: Neither targetMailbox nor targetMailboxPath defined.');
+        'move() error: Neither targetMailbox nor targetMailboxPath defined.',
+      );
     }
+
     return _copyOrMove(
       'MOVE',
       sequence,
@@ -547,6 +562,7 @@ class ImapClient extends ClientBase {
       throw InvalidArgumentException('uidMove() error: Neither targetMailbox '
           'nor targetMailboxPath defined.');
     }
+
     return _copyOrMove(
       'UID MOVE',
       sequence,
@@ -571,7 +587,10 @@ class ImapClient extends ClientBase {
       ..write(' ');
     sequence.render(buffer);
     final path = _encodeFirstMailboxPath(
-        targetMailbox, targetMailboxPath, selectedMailbox);
+      targetMailbox,
+      targetMailboxPath,
+      selectedMailbox,
+    );
     buffer
       ..write(' ')
       ..write(path);
@@ -579,8 +598,11 @@ class ImapClient extends ClientBase {
       buffer.toString(), writeTimeout: defaultWriteTimeout,
       // Use response timeout here? This could be a long running operation...
     );
+
     return sendCommand<GenericImapResult>(
-        cmd, GenericParser(this, selectedMailbox));
+      cmd,
+      GenericParser(this, selectedMailbox),
+    );
   }
 
   /// Updates the [flags] of the message(s) from the specified [sequence]
@@ -1161,6 +1183,7 @@ class ImapClient extends ClientBase {
       writeTimeout: defaultWriteTimeout,
       responseTimeout: defaultResponseTimeout,
     );
+
     return sendCommand<Mailbox?>(cmd, NoopParser(this, _selectedMailbox));
   }
 
@@ -1184,6 +1207,7 @@ class ImapClient extends ClientBase {
       'CHECK',
       writeTimeout: defaultWriteTimeout,
     );
+
     return sendCommand<Mailbox?>(cmd, NoopParser(this, _selectedMailbox));
   }
 
@@ -1199,6 +1223,7 @@ class ImapClient extends ClientBase {
       writeTimeout: defaultWriteTimeout,
       responseTimeout: defaultResponseTimeout,
     );
+
     return sendCommand<Mailbox?>(cmd, NoopParser(this, _selectedMailbox));
   }
 
@@ -1221,6 +1246,7 @@ class ImapClient extends ClientBase {
       writeTimeout: defaultWriteTimeout,
       responseTimeout: defaultResponseTimeout,
     );
+
     return sendCommand<Mailbox?>(cmd, NoopParser(this, _selectedMailbox));
   }
 
@@ -1242,22 +1268,33 @@ class ImapClient extends ClientBase {
   ///
   /// The LIST command will set the [serverInfo]`.pathSeparator`
   /// as a side-effect.
-  Future<List<Mailbox>> listMailboxes(
-          {String path = '""',
-          bool recursive = false,
-          List<String>? mailboxPatterns,
-          List<String>? selectionOptions,
-          List<ReturnOption>? returnOptions}) =>
-      listMailboxesByReferenceAndName(path, recursive ? '*' : '%',
-          mailboxPatterns, selectionOptions, returnOptions);
+  Future<List<Mailbox>> listMailboxes({
+    String path = '""',
+    bool recursive = false,
+    List<String>? mailboxPatterns,
+    List<String>? selectionOptions,
+    List<ReturnOption>? returnOptions,
+  }) =>
+      listMailboxesByReferenceAndName(
+        path,
+        recursive ? '*' : '%',
+        mailboxPatterns,
+        selectionOptions,
+        returnOptions,
+      );
 
   String _encodeFirstMailboxPath(
-      Mailbox? preferred, String? path, Mailbox? third) {
+    Mailbox? preferred,
+    String? path,
+    Mailbox? third,
+  ) {
     if (preferred == null && path == null && third == null) {
       throw ImapException(this, 'Invalid mailbox null');
     }
+
     return _encodeMailboxPath(
-        preferred?.encodedPath ?? path ?? third!.encodedPath);
+      preferred?.encodedPath ?? path ?? third?.encodedPath ?? '',
+    );
   }
 
   String _encodeMailboxPath(String path, [bool alwaysQuote = false]) {
@@ -1265,6 +1302,7 @@ class ImapClient extends ClientBase {
       if (path.startsWith('\"')) {
         return path;
       }
+
       return '"$path"';
     }
     final pathSeparator = serverInfo.pathSeparator ?? '/';
@@ -1273,6 +1311,7 @@ class ImapClient extends ClientBase {
         (alwaysQuote && !encodedPath.startsWith('"'))) {
       encodedPath = '"$encodedPath"';
     }
+
     return encodedPath;
   }
 
@@ -1283,10 +1322,12 @@ class ImapClient extends ClientBase {
   /// can be provided with [returnOptions].
   /// The LIST command will set the `serverInfo.pathSeparator` as a side-effect
   Future<List<Mailbox>> listMailboxesByReferenceAndName(
-      String referenceName, String mailboxName,
-      [List<String>? mailboxPatterns,
-      List<String>? selectionOptions,
-      List<ReturnOption>? returnOptions]) {
+    String referenceName,
+    String mailboxName, [
+    List<String>? mailboxPatterns,
+    List<String>? selectionOptions,
+    List<ReturnOption>? returnOptions,
+  ]) {
     final buffer = StringBuffer('LIST');
     final bool hasSelectionOptions;
     if (selectionOptions != null && selectionOptions.isNotEmpty) {
@@ -1307,7 +1348,8 @@ class ImapClient extends ClientBase {
       buffer
         ..write(' (')
         ..write(
-            mailboxPatterns.map((e) => _encodeMailboxPath(e, true)).join(' '))
+          mailboxPatterns.map((e) => _encodeMailboxPath(e, true)).join(' '),
+        )
         ..write(')');
     } else {
       hasMailboxPatterns = false;
@@ -1330,10 +1372,12 @@ class ImapClient extends ClientBase {
       writeTimeout: defaultWriteTimeout,
       responseTimeout: defaultResponseTimeout,
     );
-    final parser = ListParser(serverInfo,
-        isExtended:
-            hasSelectionOptions || hasMailboxPatterns || hasReturnOptions,
-        hasReturnOptions: hasReturnOptions);
+    final parser = ListParser(
+      serverInfo,
+      isExtended: hasSelectionOptions || hasMailboxPatterns || hasReturnOptions,
+      hasReturnOptions: hasReturnOptions,
+    );
+
     return sendCommand<List<Mailbox>>(cmd, parser);
   }
 
@@ -1343,8 +1387,10 @@ class ImapClient extends ClientBase {
   /// if there is none selected, then the root is used.
   /// When [recursive] is true, then all sub-mailboxes are also listed.
   /// The LIST command will set the `serverInfo.pathSeparator` as a side-effect
-  Future<List<Mailbox>> listSubscribedMailboxes(
-      {String path = '""', bool recursive = false}) {
+  Future<List<Mailbox>> listSubscribedMailboxes({
+    String path = '""',
+    bool recursive = false,
+  }) {
     // list all folders in that path
     final cmd = Command(
       'LSUB ${_encodeMailboxPath(path)} ${recursive ? '*' : '%'}',
@@ -1352,6 +1398,7 @@ class ImapClient extends ClientBase {
       responseTimeout: defaultResponseTimeout,
     );
     final parser = ListParser(serverInfo, isLsubParser: true);
+
     return sendCommand<List<Mailbox>>(cmd, parser);
   }
 
@@ -1373,6 +1420,7 @@ class ImapClient extends ClientBase {
       responseTimeout: defaultResponseTimeout,
     );
     final parser = EnableParser(serverInfo);
+
     return sendCommand<List<Capability>>(cmd, parser);
   }
 
@@ -1387,8 +1435,11 @@ class ImapClient extends ClientBase {
   /// capability and you have known values from the last session.
   /// Note that you need to `ENABLE QRESYNC` first.
   /// Compare [enable]
-  Future<Mailbox> selectMailboxByPath(String path,
-      {bool enableCondStore = false, QResyncParameters? qresync}) async {
+  Future<Mailbox> selectMailboxByPath(
+    String path, {
+    bool enableCondStore = false,
+    QResyncParameters? qresync,
+  }) async {
     if (serverInfo.pathSeparator == null) {
       await listMailboxes();
     }
@@ -1402,8 +1453,12 @@ class ImapClient extends ClientBase {
       pathSeparator: pathSeparator,
       flags: [],
     );
-    return selectMailbox(box,
-        enableCondStore: enableCondStore, qresync: qresync);
+
+    return selectMailbox(
+      box,
+      enableCondStore: enableCondStore,
+      qresync: qresync,
+    );
   }
 
   /// Selects the inbox.
@@ -1416,10 +1471,15 @@ class ImapClient extends ClientBase {
   /// capability and you have known values from the last session.
   /// Note that you need to `ENABLE QRESYNC` first.
   /// Compare [enable]
-  Future<Mailbox> selectInbox(
-          {bool enableCondStore = false, QResyncParameters? qresync}) =>
-      selectMailboxByPath('INBOX',
-          enableCondStore: enableCondStore, qresync: qresync);
+  Future<Mailbox> selectInbox({
+    bool enableCondStore = false,
+    QResyncParameters? qresync,
+  }) =>
+      selectMailboxByPath(
+        'INBOX',
+        enableCondStore: enableCondStore,
+        qresync: qresync,
+      );
 
   /// Selects the specified mailbox.
   ///
@@ -1432,10 +1492,17 @@ class ImapClient extends ClientBase {
   /// capability and you have known values from the last session.
   /// Note that you need to `ENABLE QRESYNC` first.
   /// Compare [enable]
-  Future<Mailbox> selectMailbox(Mailbox box,
-          {bool enableCondStore = false, QResyncParameters? qresync}) =>
-      _selectOrExamine('SELECT', box,
-          enableCondStore: enableCondStore, qresync: qresync);
+  Future<Mailbox> selectMailbox(
+    Mailbox box, {
+    bool enableCondStore = false,
+    QResyncParameters? qresync,
+  }) =>
+      _selectOrExamine(
+        'SELECT',
+        box,
+        enableCondStore: enableCondStore,
+        qresync: qresync,
+      );
 
   /// Examines the [box] without selecting it.
   ///
@@ -1452,14 +1519,25 @@ class ImapClient extends ClientBase {
   /// per-user state, are permitted; in particular, EXAMINE MUST NOT
   /// cause messages to lose the `\Recent` flag.
   /// Compare [enable]
-  Future<Mailbox> examineMailbox(Mailbox box,
-          {bool enableCondStore = false, QResyncParameters? qresync}) =>
-      _selectOrExamine('EXAMINE', box,
-          enableCondStore: enableCondStore, qresync: qresync);
+  Future<Mailbox> examineMailbox(
+    Mailbox box, {
+    bool enableCondStore = false,
+    QResyncParameters? qresync,
+  }) =>
+      _selectOrExamine(
+        'EXAMINE',
+        box,
+        enableCondStore: enableCondStore,
+        qresync: qresync,
+      );
 
   /// implementation for both SELECT as well as EXAMINE
-  Future<Mailbox> _selectOrExamine(String command, Mailbox box,
-      {bool enableCondStore = false, QResyncParameters? qresync}) {
+  Future<Mailbox> _selectOrExamine(
+    String command,
+    Mailbox box, {
+    bool enableCondStore = false,
+    QResyncParameters? qresync,
+  }) {
     final path = '"${box.encodedPath}"';
     final buffer = StringBuffer()
       ..write(command)
@@ -1485,6 +1563,7 @@ class ImapClient extends ClientBase {
       writeTimeout: defaultWriteTimeout,
       responseTimeout: defaultResponseTimeout,
     );
+
     return sendCommand<Mailbox>(cmd, parser);
   }
 
@@ -1504,6 +1583,7 @@ class ImapClient extends ClientBase {
     );
     final parser = NoResponseParser(_selectedMailbox);
     _selectedMailbox = null;
+
     return sendCommand(cmd, parser);
   }
 
@@ -1522,6 +1602,7 @@ class ImapClient extends ClientBase {
     );
     final parser = NoResponseParser(_selectedMailbox);
     _selectedMailbox = null;
+
     return sendCommand(cmd, parser);
   }
 
@@ -1532,10 +1613,11 @@ class ImapClient extends ClientBase {
   /// extended search. Note that the IMAP server needs to support
   /// [ESEARCH](https://tools.ietf.org/html/rfc4731) capability for this.
   /// This request times out after the specified [responseTimeout]
-  Future<SearchImapResult> searchMessages(
-      {String searchCriteria = 'UNSEEN',
-      List<ReturnOption>? returnOptions,
-      Duration? responseTimeout}) {
+  Future<SearchImapResult> searchMessages({
+    String searchCriteria = 'UNSEEN',
+    List<ReturnOption>? returnOptions,
+    Duration? responseTimeout,
+  }) {
     final parser =
         SearchParser(isUidSearch: false, isExtended: returnOptions != null);
     final buffer = StringBuffer('SEARCH ');
@@ -1549,20 +1631,18 @@ class ImapClient extends ClientBase {
     final cmdText = buffer.toString();
     buffer.clear();
     final searchLines = cmdText.split('\n');
-    Command cmd;
-    if (searchLines.length == 1) {
-      cmd = Command(
-        cmdText,
-        writeTimeout: defaultWriteTimeout,
-        responseTimeout: responseTimeout,
-      );
-    } else {
-      cmd = Command.withContinuation(
-        searchLines,
-        writeTimeout: defaultWriteTimeout,
-        responseTimeout: responseTimeout,
-      );
-    }
+    final cmd = searchLines.length == 1
+        ? Command(
+            cmdText,
+            writeTimeout: defaultWriteTimeout,
+            responseTimeout: responseTimeout,
+          )
+        : Command.withContinuation(
+            searchLines,
+            writeTimeout: defaultWriteTimeout,
+            responseTimeout: responseTimeout,
+          );
+
     return sendCommand<SearchImapResult>(cmd, parser);
   }
 
@@ -1570,10 +1650,14 @@ class ImapClient extends ClientBase {
   ///
   /// Specify a [responseTimeout] when a response is expected
   /// within the given time.
-  Future<SearchImapResult> searchMessagesWithQuery(SearchQueryBuilder query,
-          {Duration? responseTimeout}) =>
+  Future<SearchImapResult> searchMessagesWithQuery(
+    SearchQueryBuilder query, {
+    Duration? responseTimeout,
+  }) =>
       searchMessages(
-          searchCriteria: query.toString(), responseTimeout: responseTimeout);
+        searchCriteria: query.toString(),
+        responseTimeout: responseTimeout,
+      );
 
   /// Searches messages by the given [searchCriteria]
   /// like `'UNSEEN'` or `'RECENT'` or `'FROM sender@domain.com'`.
@@ -1582,10 +1666,11 @@ class ImapClient extends ClientBase {
   /// When augmented with zero or more [returnOptions], requests an
   /// extended search.
   /// This request times out after the specified [responseTimeout]
-  Future<SearchImapResult> uidSearchMessages(
-      {String searchCriteria = 'UNSEEN',
-      List<ReturnOption>? returnOptions,
-      Duration? responseTimeout}) {
+  Future<SearchImapResult> uidSearchMessages({
+    String searchCriteria = 'UNSEEN',
+    List<ReturnOption>? returnOptions,
+    Duration? responseTimeout,
+  }) {
     final parser =
         SearchParser(isUidSearch: true, isExtended: returnOptions != null);
     final buffer = StringBuffer('UID SEARCH ');
@@ -1599,20 +1684,18 @@ class ImapClient extends ClientBase {
     final cmdText = buffer.toString();
     buffer.clear();
     final searchLines = cmdText.split('\n');
-    Command cmd;
-    if (searchLines.length == 1) {
-      cmd = Command(
-        cmdText,
-        writeTimeout: defaultWriteTimeout,
-        responseTimeout: responseTimeout,
-      );
-    } else {
-      cmd = Command.withContinuation(
-        searchLines,
-        writeTimeout: defaultWriteTimeout,
-        responseTimeout: responseTimeout,
-      );
-    }
+    final cmd = searchLines.length == 1
+        ? Command(
+            cmdText,
+            writeTimeout: defaultWriteTimeout,
+            responseTimeout: responseTimeout,
+          )
+        : Command.withContinuation(
+            searchLines,
+            writeTimeout: defaultWriteTimeout,
+            responseTimeout: responseTimeout,
+          );
+
     return sendCommand<SearchImapResult>(cmd, parser);
   }
 
@@ -1621,12 +1704,16 @@ class ImapClient extends ClientBase {
   /// Is only supported by servers that expose the `UID` capability.
   /// Specify a [responseTimeout] when a response is expected within
   /// the given time.
-  Future<SearchImapResult> uidSearchMessagesWithQuery(SearchQueryBuilder query,
-          {List<ReturnOption>? returnOptions, Duration? responseTimeout}) =>
+  Future<SearchImapResult> uidSearchMessagesWithQuery(
+    SearchQueryBuilder query, {
+    List<ReturnOption>? returnOptions,
+    Duration? responseTimeout,
+  }) =>
       uidSearchMessages(
-          searchCriteria: query.toString(),
-          returnOptions: returnOptions,
-          responseTimeout: responseTimeout);
+        searchCriteria: query.toString(),
+        returnOptions: returnOptions,
+        responseTimeout: responseTimeout,
+      );
 
   /// Fetches a single message by the given definition.
   ///
@@ -1637,11 +1724,15 @@ class ImapClient extends ClientBase {
   /// Specify a [responseTimeout] when a response is expected within the
   /// given time.
   Future<FetchImapResult> fetchMessage(
-          int messageSequenceId, String fetchContentDefinition,
-          {Duration? responseTimeout}) =>
+    int messageSequenceId,
+    String fetchContentDefinition, {
+    Duration? responseTimeout,
+  }) =>
       fetchMessages(
-          MessageSequence.fromId(messageSequenceId), fetchContentDefinition,
-          responseTimeout: responseTimeout);
+        MessageSequence.fromId(messageSequenceId),
+        fetchContentDefinition,
+        responseTimeout: responseTimeout,
+      );
 
   /// Fetches messages by the given definition.
   ///
@@ -1654,16 +1745,29 @@ class ImapClient extends ClientBase {
   /// Specify a [responseTimeout] when a response is expected within the
   /// given time.
   Future<FetchImapResult> fetchMessages(
-          MessageSequence sequence, String? fetchContentDefinition,
-          {int? changedSinceModSequence, Duration? responseTimeout}) =>
-      _fetchMessages(false, 'FETCH', sequence, fetchContentDefinition,
-          changedSinceModSequence: changedSinceModSequence,
-          responseTimeout: responseTimeout);
+    MessageSequence sequence,
+    String? fetchContentDefinition, {
+    int? changedSinceModSequence,
+    Duration? responseTimeout,
+  }) =>
+      _fetchMessages(
+        false,
+        'FETCH',
+        sequence,
+        fetchContentDefinition,
+        changedSinceModSequence: changedSinceModSequence,
+        responseTimeout: responseTimeout,
+      );
 
   /// FETCH and UID FETCH implementation
-  Future<FetchImapResult> _fetchMessages(bool isUidFetch, String command,
-      MessageSequence sequence, String? fetchContentDefinition,
-      {int? changedSinceModSequence, Duration? responseTimeout}) {
+  Future<FetchImapResult> _fetchMessages(
+    bool isUidFetch,
+    String command,
+    MessageSequence sequence,
+    String? fetchContentDefinition, {
+    int? changedSinceModSequence,
+    Duration? responseTimeout,
+  }) {
     final cmdText = StringBuffer()
       ..write(command)
       ..write(' ');
@@ -1683,6 +1787,7 @@ class ImapClient extends ClientBase {
       responseTimeout: responseTimeout,
     );
     final parser = FetchParser(isUidFetch: isUidFetch);
+
     return sendCommand<FetchImapResult>(cmd, parser);
   }
 
@@ -1694,14 +1799,17 @@ class ImapClient extends ClientBase {
   /// '1:* (FLAGS ENVELOPE) (CHANGEDSINCE 1232232)'.
   /// Specify a [responseTimeout] when a response is expected within
   /// the given time.
-  Future<FetchImapResult> fetchMessagesByCriteria(String fetchIdsAndCriteria,
-      {Duration? responseTimeout}) {
+  Future<FetchImapResult> fetchMessagesByCriteria(
+    String fetchIdsAndCriteria, {
+    Duration? responseTimeout,
+  }) {
     final cmd = Command(
       'FETCH $fetchIdsAndCriteria',
       writeTimeout: defaultWriteTimeout,
       responseTimeout: responseTimeout,
     );
     final parser = FetchParser(isUidFetch: false);
+
     return sendCommand<FetchImapResult>(cmd, parser);
   }
 
@@ -1715,25 +1823,31 @@ class ImapClient extends ClientBase {
   ///
   /// Specify a [responseTimeout] when a response is expected within the
   /// given time.
-  Future<FetchImapResult> fetchRecentMessages(
-      {int messageCount = 30,
-      String criteria = '(FLAGS BODY[])',
-      Duration? responseTimeout}) {
+  Future<FetchImapResult> fetchRecentMessages({
+    int messageCount = 30,
+    String criteria = '(FLAGS BODY[])',
+    Duration? responseTimeout,
+  }) {
     final box = _selectedMailbox;
     if (box == null) {
       throw InvalidArgumentException(
-          'No mailbox selected - call select() first.');
+        'No mailbox selected - call select() first.',
+      );
     }
     final upperMessageSequenceId = box.messagesExists;
     var lowerMessageSequenceId = upperMessageSequenceId - messageCount;
     if (lowerMessageSequenceId < 1) {
       lowerMessageSequenceId = 1;
     }
+
     return fetchMessages(
-        MessageSequence.fromRange(
-            lowerMessageSequenceId, upperMessageSequenceId),
-        criteria,
-        responseTimeout: responseTimeout);
+      MessageSequence.fromRange(
+        lowerMessageSequenceId,
+        upperMessageSequenceId,
+      ),
+      criteria,
+      responseTimeout: responseTimeout,
+    );
   }
 
   /// Fetches a single messages identified by the [messageUid]
@@ -1746,11 +1860,17 @@ class ImapClient extends ClientBase {
   /// Specify a [responseTimeout] when a response is expected within the
   /// given time.
   Future<FetchImapResult> uidFetchMessage(
-          int messageUid, String fetchContentDefinition,
-          {Duration? responseTimeout}) =>
-      _fetchMessages(true, 'UID FETCH', MessageSequence.fromId(messageUid),
-          fetchContentDefinition,
-          responseTimeout: responseTimeout);
+    int messageUid,
+    String fetchContentDefinition, {
+    Duration? responseTimeout,
+  }) =>
+      _fetchMessages(
+        true,
+        'UID FETCH',
+        MessageSequence.fromId(messageUid),
+        fetchContentDefinition,
+        responseTimeout: responseTimeout,
+      );
 
   /// Fetches messages by the given definition.
   ///
@@ -1765,8 +1885,11 @@ class ImapClient extends ClientBase {
   /// specified duration.
   /// Also compare [uidFetchMessagesByCriteria].
   Future<FetchImapResult> uidFetchMessages(
-          MessageSequence sequence, String? fetchContentDefinition,
-          {int? changedSinceModSequence, Duration? responseTimeout}) =>
+    MessageSequence sequence,
+    String? fetchContentDefinition, {
+    int? changedSinceModSequence,
+    Duration? responseTimeout,
+  }) =>
       _fetchMessages(
         true,
         'UID FETCH',
@@ -1783,14 +1906,17 @@ class ImapClient extends ClientBase {
   /// the requested elements, e.g. '1232:1234 (ENVELOPE)'.
   /// Specify a [responseTimeout] when a response is expected within the
   /// given time.
-  Future<FetchImapResult> uidFetchMessagesByCriteria(String fetchIdsAndCriteria,
-      {Duration? responseTimeout}) {
+  Future<FetchImapResult> uidFetchMessagesByCriteria(
+    String fetchIdsAndCriteria, {
+    Duration? responseTimeout,
+  }) {
     final cmd = Command(
       'UID FETCH $fetchIdsAndCriteria',
       writeTimeout: defaultWriteTimeout,
       responseTimeout: responseTimeout,
     );
     final parser = FetchParser(isUidFetch: true);
+
     return sendCommand<FetchImapResult>(cmd, parser);
   }
 
@@ -1833,7 +1959,10 @@ class ImapClient extends ClientBase {
     Duration? responseTimeout,
   }) {
     final path = _encodeFirstMailboxPath(
-        targetMailbox, targetMailboxPath, _selectedMailbox);
+      targetMailbox,
+      targetMailboxPath,
+      _selectedMailbox,
+    );
     final buffer = StringBuffer()
       ..write('APPEND ')
       ..write(path);
@@ -1849,10 +1978,15 @@ class ImapClient extends ClientBase {
       ..write(numberOfBytes)
       ..write('}');
     final cmdText = buffer.toString();
-    final cmd = Command.withContinuation([cmdText, messageText],
-        responseTimeout: responseTimeout);
+    final cmd = Command.withContinuation(
+      [cmdText, messageText],
+      responseTimeout: responseTimeout,
+    );
+
     return sendCommand<GenericImapResult>(
-        cmd, GenericParser(this, _selectedMailbox));
+      cmd,
+      GenericParser(this, _selectedMailbox),
+    );
   }
 
   /// Retrieves the specified meta data entry.
@@ -1862,8 +1996,12 @@ class ImapClient extends ClientBase {
   ///
   /// Compare https://tools.ietf.org/html/rfc5464 for details.
   /// Note that errata of the RFC exist.
-  Future<List<MetaDataEntry>> getMetaData(String entry,
-      {String? mailboxName, int? maxSize, MetaDataDepth? depth}) {
+  Future<List<MetaDataEntry>> getMetaData(
+    String entry, {
+    String? mailboxName,
+    int? maxSize,
+    MetaDataDepth? depth,
+  }) {
     var cmd = 'GETMETADATA ';
     if (maxSize != null || depth != null) {
       cmd += '(';
@@ -1893,6 +2031,7 @@ class ImapClient extends ClientBase {
     }
     cmd += '"${mailboxName ?? ''}" ($entry)';
     final parser = MetaDataParser();
+
     return sendCommand<List<MetaDataEntry>>(Command(cmd), parser);
   }
 
@@ -1907,7 +2046,7 @@ class ImapClient extends ClientBase {
   /// Compare https://tools.ietf.org/html/rfc5464 for details.
   Future<Mailbox?> setMetaData(MetaDataEntry entry) {
     final valueText = entry.valueText;
-    Command cmd;
+    final Command cmd;
     final value = entry.value;
     if (value == null || _isSafeForQuotedTransmission(valueText ?? '')) {
       final cmdText = 'SETMETADATA "${entry.mailboxName}" '
@@ -1922,6 +2061,7 @@ class ImapClient extends ClientBase {
       cmd = Command.withContinuation(parts);
     }
     final parser = NoResponseParser(_selectedMailbox);
+
     return sendCommand(cmd, parser);
   }
 
@@ -1955,11 +2095,10 @@ class ImapClient extends ClientBase {
     parts.add(cmd.toString());
     final parser = NoopParser(this, _selectedMailbox);
     Command command;
-    if (parts.length == 1) {
-      command = Command(parts.first);
-    } else {
-      command = Command.withContinuation(parts);
-    }
+    command = parts.length == 1
+        ? Command(parts.first)
+        : Command.withContinuation(parts);
+
     return sendCommand<Mailbox?>(command, parser);
   }
 
@@ -2015,6 +2154,7 @@ class ImapClient extends ClientBase {
       responseTimeout: defaultResponseTimeout,
     );
     final parser = StatusParser(box);
+
     return sendCommand<Mailbox>(cmd, parser);
   }
 
@@ -2042,9 +2182,10 @@ class ImapClient extends ClientBase {
       return matchingBoxes.first;
     }
     throw ImapException(
-        this,
-        'Unable to find just created mailbox with the path [$path]. '
-        'Please report this problem.');
+      this,
+      'Unable to find just created mailbox with the path [$path]. '
+      'Please report this problem.',
+    );
   }
 
   /// Removes the specified mailbox
@@ -2069,17 +2210,18 @@ class ImapClient extends ClientBase {
       cmd,
       NoopParser(this, _selectedMailbox ?? box),
     );
-    if (box.name.toUpperCase() == 'INBOX') {
-      /* Renaming INBOX is permitted, and has special behavior.  It moves
+    // if (box.name.toUpperCase() == 'INBOX') {
+    /* Renaming INBOX is permitted, and has special behavior.  It moves
         all messages in INBOX to a new mailbox with the given name,
         leaving INBOX empty.  If the server implementation supports
         inferior hierarchical names of INBOX, these are unaffected by a
         rename of INBOX.
         */
-      // question: do we need to create a new mailbox
-      // and return that one instead?
-    }
-    return response!;
+    // question: do we need to create a new mailbox
+    // and return that one instead?
+    // }
+
+    return response ?? box;
   }
 
   /// Subscribes the specified mailbox.
@@ -2121,10 +2263,12 @@ class ImapClient extends ClientBase {
     }
     if (_selectedMailbox == null) {
       print('$logName: idleStart(): ERROR: no mailbox selected');
+
       return Future.value();
     }
     if (_isInIdleMode) {
       logApp('Warning: idleStart() called but client is already in IDLE mode.');
+
       return Future.value();
     }
     final cmd = Command(
@@ -2136,6 +2280,7 @@ class ImapClient extends ClientBase {
     _idleCommandTask = task;
     final result = sendCommandTask(task, returnCompleter: false);
     _isInIdleMode = true;
+
     return result;
   }
 
@@ -2152,6 +2297,7 @@ class ImapClient extends ClientBase {
     }
     if (!_isInIdleMode) {
       print('$logName: warning: ignore idleDone(): not in IDLE mode');
+
       return;
     }
     _isInIdleMode = false;
@@ -2166,7 +2312,9 @@ class ImapClient extends ClientBase {
     }
     if (completer != null) {
       completer.timeout(
-          defaultResponseTimeout ?? const Duration(seconds: 4), this);
+        defaultResponseTimeout ?? const Duration(seconds: 4),
+        this,
+      );
       await completer.future;
     } else {
       await Future.delayed(const Duration(milliseconds: 200));
@@ -2178,8 +2326,10 @@ class ImapClient extends ClientBase {
   ///
   /// Optionally define the [quotaRoot] which defaults to `""`.
   /// Note that the server needs to support the [QUOTA](https://tools.ietf.org/html/rfc2087) capability.
-  Future<QuotaResult> setQuota(
-      {required Map<String, int> resourceLimits, String quotaRoot = '""'}) {
+  Future<QuotaResult> setQuota({
+    required Map<String, int> resourceLimits,
+    String quotaRoot = '""',
+  }) {
     final quotaRootParameter =
         quotaRoot.contains(' ') ? '"$quotaRoot"' : quotaRoot;
     final buffer = StringBuffer()
@@ -2196,6 +2346,7 @@ class ImapClient extends ClientBase {
       responseTimeout: defaultResponseTimeout,
     );
     final parser = QuotaParser();
+
     return sendCommand<QuotaResult>(cmd, parser);
   }
 
@@ -2213,6 +2364,7 @@ class ImapClient extends ClientBase {
       responseTimeout: defaultResponseTimeout,
     );
     final parser = QuotaParser();
+
     return sendCommand<QuotaResult>(cmd, parser);
   }
 
@@ -2228,6 +2380,7 @@ class ImapClient extends ClientBase {
       responseTimeout: defaultResponseTimeout,
     );
     final parser = QuotaRootParser();
+
     return sendCommand<QuotaRootResult>(cmd, parser);
   }
 
@@ -2246,10 +2399,12 @@ class ImapClient extends ClientBase {
   /// The server needs to expose the
   /// [SORT](https://tools.ietf.org/html/rfc5256) capability for this
   /// command to work.
-  Future<SortImapResult> sortMessages(String sortCriteria,
-      [String searchCriteria = 'ALL',
-      String charset = 'UTF-8',
-      List<ReturnOption>? returnOptions]) {
+  Future<SortImapResult> sortMessages(
+    String sortCriteria, [
+    String searchCriteria = 'ALL',
+    String charset = 'UTF-8',
+    List<ReturnOption>? returnOptions,
+  ]) {
     final parser =
         SortParser(isUidSort: false, isExtended: returnOptions != null);
     final buffer = StringBuffer('SORT ');
@@ -2269,18 +2424,13 @@ class ImapClient extends ClientBase {
     final cmdText = buffer.toString();
     buffer.clear();
     final sortLines = cmdText.split('\n');
-    Command cmd;
-    if (sortLines.length == 1) {
-      cmd = Command(
-        cmdText,
-        writeTimeout: defaultWriteTimeout,
-      );
-    } else {
-      cmd = Command.withContinuation(
-        sortLines,
-        writeTimeout: defaultWriteTimeout,
-      );
-    }
+    final cmd = sortLines.length == 1
+        ? Command(cmdText, writeTimeout: defaultWriteTimeout)
+        : Command.withContinuation(
+            sortLines,
+            writeTimeout: defaultWriteTimeout,
+          );
+
     return sendCommand<SortImapResult>(cmd, parser);
   }
 
@@ -2295,10 +2445,12 @@ class ImapClient extends ClientBase {
   /// The server needs to expose the
   /// [SORT](https://tools.ietf.org/html/rfc5256) capability for this
   /// command to work.
-  Future<SortImapResult> uidSortMessages(String sortCriteria,
-      [String searchCriteria = 'ALL',
-      String charset = 'UTF-8',
-      List<ReturnOption>? returnOptions]) {
+  Future<SortImapResult> uidSortMessages(
+    String sortCriteria, [
+    String searchCriteria = 'ALL',
+    String charset = 'UTF-8',
+    List<ReturnOption>? returnOptions,
+  ]) {
     final parser =
         SortParser(isUidSort: true, isExtended: returnOptions != null);
     final buffer = StringBuffer('UID SORT ');
@@ -2318,18 +2470,13 @@ class ImapClient extends ClientBase {
     final cmdText = buffer.toString();
     buffer.clear();
     final sortLines = cmdText.split('\n');
-    Command cmd;
-    if (sortLines.length == 1) {
-      cmd = Command(
-        cmdText,
-        writeTimeout: defaultWriteTimeout,
-      );
-    } else {
-      cmd = Command.withContinuation(
-        sortLines,
-        writeTimeout: defaultWriteTimeout,
-      );
-    }
+    final cmd = sortLines.length == 1
+        ? Command(cmdText, writeTimeout: defaultWriteTimeout)
+        : Command.withContinuation(
+            sortLines,
+            writeTimeout: defaultWriteTimeout,
+          );
+
     return sendCommand<SortImapResult>(cmd, parser);
   }
 
@@ -2364,13 +2511,15 @@ class ImapClient extends ClientBase {
       ..write(charset)
       ..write(' SINCE ')
       ..write(DateCodec.encodeSearchDate(since));
+
     return sendCommand(
-        Command(
-          buffer.toString(),
-          writeTimeout: defaultWriteTimeout,
-          responseTimeout: responseTimeout,
-        ),
-        ThreadParser(isUidSequence: threadUids));
+      Command(
+        buffer.toString(),
+        writeTimeout: defaultWriteTimeout,
+        responseTimeout: responseTimeout,
+      ),
+      ThreadParser(isUidSequence: threadUids),
+    );
   }
 
   /// Requests the UIDs of message threads starting on [since]
@@ -2391,15 +2540,17 @@ class ImapClient extends ClientBase {
     Duration? responseTimeout,
   }) =>
       threadMessages(
-          method: method,
-          charset: charset,
-          since: since,
-          threadUids: true,
-          responseTimeout: responseTimeout);
+        method: method,
+        charset: charset,
+        since: since,
+        threadUids: true,
+        responseTimeout: responseTimeout,
+      );
 
   /// Retrieves the next session-unique command ID
   String nextId() {
     final id = _lastUsedCommandId++;
+
     return 'a$id';
   }
 
@@ -2416,11 +2567,8 @@ class ImapClient extends ClientBase {
     final task = CommandTask<T>(command, nextId(), parser);
     _tasks[task.id] = task;
     queueTask(task);
-    if (returnCompleter) {
-      return task.completer.future;
-    } else {
-      return Future<T>.value();
-    }
+
+    return returnCompleter ? task.completer.future : Future<T>.value();
   }
 
   /// Queues the given [task] for sending to the server.
@@ -2433,11 +2581,8 @@ class ImapClient extends ClientBase {
     bool returnCompleter = true,
   }) {
     queueTask(task);
-    if (returnCompleter) {
-      return task.completer.future;
-    } else {
-      return Future<T>.value();
-    }
+
+    return returnCompleter ? task.completer.future : Future<T>.value();
   }
 
   /// Queues the given [task].
@@ -2447,12 +2592,14 @@ class ImapClient extends ClientBase {
     if (_isInIdleMode && task.command.commandText == 'IDLE') {
       logApp('Ignore duplicate IDLE: $task');
       task.completer.complete();
+
       return;
     }
     final stashedQueue = _stashedQueue;
     if (!isConnected && stashedQueue != null) {
       logApp('Stashing task $task');
       stashedQueue.add(task);
+
       return;
     }
     _queue.add(task);
@@ -2482,6 +2629,7 @@ class ImapClient extends ClientBase {
       if (!task.completer.isCompleted) {
         task.completer.completeError(e, s);
       }
+
       return;
     }
     try {
@@ -2576,6 +2724,7 @@ class ImapClient extends ClientBase {
       final response = cmd.getContinuationResponse(imapResponse);
       if (response != null) {
         await writeText(response);
+
         return;
       }
     }
@@ -2588,6 +2737,7 @@ class ImapClient extends ClientBase {
   @Deprecated('Use disconnect() instead.')
   Future<dynamic> closeConnection() {
     logApp('Closing socket for host ${serverInfo.host}');
+
     return disconnect();
   }
 
diff --git a/lib/src/imap/imap_exception.dart b/lib/src/imap/imap_exception.dart
index 91dca764..4e54bcc0 100644
--- a/lib/src/imap/imap_exception.dart
+++ b/lib/src/imap/imap_exception.dart
@@ -30,6 +30,7 @@ class ImapException implements Exception {
         ..write('\n')
         ..write(stackTrace);
     }
+
     return buffer.toString();
   }
 }
diff --git a/lib/src/imap/imap_search.dart b/lib/src/imap/imap_search.dart
index 2e31955a..8e85c90f 100644
--- a/lib/src/imap/imap_search.dart
+++ b/lib/src/imap/imap_search.dart
@@ -198,6 +198,7 @@ class SearchQueryBuilder {
   String toString() {
     final buffer = StringBuffer();
     render(buffer);
+
     return buffer.toString();
   }
 }
@@ -226,9 +227,11 @@ class _TextSearchTerm extends SearchTerm {
     // check if there are UTF-8 characters:
     if (containsNonAsciiCharacters(value)) {
       final encoded = utf8.encode(value);
+
       return '$name {${encoded.length}}\n$value';
     }
     final escaped = value.replaceAll('"', r'\"');
+
     return '$name "$escaped"';
   }
 
@@ -239,6 +242,7 @@ class _TextSearchTerm extends SearchTerm {
         return true;
       }
     }
+
     return false;
   }
 }
@@ -368,6 +372,7 @@ class SearchTermOr extends SearchTerm {
     if (term1 is SearchTermOr || term2 is SearchTermOr) {
       throw InvalidArgumentException('You cannot nest several OR search terms');
     }
+
     return 'OR ${term1.term} ${term2.term}';
   }
 }
diff --git a/lib/src/imap/mailbox.dart b/lib/src/imap/mailbox.dart
index 46d93646..e55d3b26 100644
--- a/lib/src/imap/mailbox.dart
+++ b/lib/src/imap/mailbox.dart
@@ -101,10 +101,11 @@ class Mailbox {
     List<MailboxFlag> flags, {
     String? pathSeparator,
   }) : this(
-            encodedName: name,
-            encodedPath: path,
-            flags: flags,
-            pathSeparator: pathSeparator ?? '/');
+          encodedName: name,
+          encodedPath: path,
+          flags: flags,
+          pathSeparator: pathSeparator ?? '/',
+        );
 
   /// Creates a new virtual mailbox
   ///
@@ -112,10 +113,11 @@ class Mailbox {
   /// a mailbox that exists for real.
   Mailbox.virtual(String name, List<MailboxFlag> flags)
       : this(
-            encodedName: name,
-            encodedPath: name,
-            flags: flags.addIfNotPresent(MailboxFlag.virtual),
-            pathSeparator: '/');
+          encodedName: name,
+          encodedPath: name,
+          flags: flags.addIfNotPresent(MailboxFlag.virtual),
+          pathSeparator: '/',
+        );
 
   /// Copies this mailbox with the given parameters
   Mailbox copyWith({
@@ -303,8 +305,12 @@ class Mailbox {
   /// from the known mailboxes (defaults to `true`).
   /// Set [createIntermediate] to `false` and  [create] to `true` to return
   /// the first known existing parent, when the direct parent is not known
-  Mailbox? getParent(List<Mailbox> knownMailboxes, String separator,
-      {bool create = true, bool createIntermediate = true}) {
+  Mailbox? getParent(
+    List<Mailbox> knownMailboxes,
+    String separator, {
+    bool create = true,
+    bool createIntermediate = true,
+  }) {
     var lastSplitIndex = encodedPath.lastIndexOf(separator);
     if (lastSplitIndex == -1) {
       // this is a root mailbox, eg 'Inbox'
@@ -325,10 +331,15 @@ class Mailbox {
         pathSeparator: separator,
       );
       if ((lastSplitIndex != -1) && (!createIntermediate)) {
-        parent = parent.getParent(knownMailboxes, separator,
-            create: true, createIntermediate: false);
+        parent = parent.getParent(
+          knownMailboxes,
+          separator,
+          create: true,
+          createIntermediate: false,
+        );
       }
     }
+
     return parent;
   }
 
@@ -344,6 +355,7 @@ class Mailbox {
       ..write(highestModSequence)
       ..write(', flags: ')
       ..write(flags);
+
     return buffer.toString();
   }
 
@@ -358,7 +370,9 @@ class Mailbox {
     } else {
       final start = path.substring(0, pathSeparatorIndex);
       final end = _modifiedUtf7Codec.encodeText(
-          path.substring(pathSeparatorIndex + pathSeparator.length));
+        path.substring(pathSeparatorIndex + pathSeparator.length),
+      );
+
       return '$start$pathSeparator$end';
     }
   }
@@ -377,6 +391,7 @@ extension _ListExtension<T> on List<T> {
     if (!contains(element)) {
       add(element);
     }
+
     return this;
   }
 }
diff --git a/lib/src/imap/message_sequence.dart b/lib/src/imap/message_sequence.dart
index fb839c41..a84cf85b 100644
--- a/lib/src/imap/message_sequence.dart
+++ b/lib/src/imap/message_sequence.dart
@@ -115,7 +115,8 @@ class MessageSequence {
             addRangeToLast(id);
           } else {
             throw InvalidArgumentException(
-                'expect id in $idText for <$chunk> in $text');
+              'expect id in $idText for <$chunk> in $text',
+            );
           }
         } else {
           final colonIndex = chunk.indexOf(':');
@@ -136,18 +137,28 @@ class MessageSequence {
   /// Convenience method for getting the sequence for a range defined by the
   /// [page] starting with `1`, the [pageSize] and the number
   /// of messages [messagesExist].
-  factory MessageSequence.fromPage(int page, int pageSize, int messagesExist,
-      {bool isUidSequence = false}) {
+  factory MessageSequence.fromPage(
+    int page,
+    int pageSize,
+    int messagesExist, {
+    bool isUidSequence = false,
+  }) {
     final rangeStart = messagesExist - page * pageSize + 1;
 
     if (page == 1) {
       // ensure that also get any new messages:
-      return MessageSequence.fromRangeToLast(rangeStart < 1 ? 1 : rangeStart,
-          isUidSequence: isUidSequence);
+      return MessageSequence.fromRangeToLast(
+        rangeStart < 1 ? 1 : rangeStart,
+        isUidSequence: isUidSequence,
+      );
     }
     final rangeEnd = rangeStart + pageSize - 1;
-    return MessageSequence.fromRange(rangeStart < 1 ? 1 : rangeStart, rangeEnd,
-        isUidSequence: isUidSequence);
+
+    return MessageSequence.fromRange(
+      rangeStart < 1 ? 1 : rangeStart,
+      rangeEnd,
+      isUidSequence: isUidSequence,
+    );
   }
 
   /// Creates a [MessageSequence] from the given [json]
@@ -187,18 +198,34 @@ class MessageSequence {
   /// Adds the UID or sequence ID of the [message] to this sequence.
   void addMessage(MimeMessage message) {
     if (isUidSequence) {
-      add(message.uid!);
+      final uid = message.uid;
+      if (uid == null) {
+        throw InvalidArgumentException('no UID found in message');
+      }
+      add(uid);
     } else {
-      add(message.sequenceId!);
+      final sequenceId = message.sequenceId;
+      if (sequenceId == null) {
+        throw InvalidArgumentException('no sequence ID found in message');
+      }
+      add(sequenceId);
     }
   }
 
   /// Removes the UID or sequence ID of the [message] to this sequence.
   void removeMessage(MimeMessage message) {
     if (isUidSequence) {
-      remove(message.uid!);
+      final uid = message.uid;
+      if (uid == null) {
+        throw InvalidArgumentException('no UID found in message');
+      }
+      remove(uid);
     } else {
-      remove(message.sequenceId!);
+      final sequenceId = message.sequenceId;
+      if (sequenceId == null) {
+        throw InvalidArgumentException('no sequence ID found in message');
+      }
+      remove(sequenceId);
     }
   }
 
@@ -255,6 +282,7 @@ class MessageSequence {
     // start:end
     if (start == end) {
       add(start);
+
       return;
     }
     final wasEmpty = isEmpty;
@@ -295,11 +323,7 @@ class MessageSequence {
     // 1:*
     final wasEmpty = isEmpty;
     _isAllAdded = true;
-    if (wasEmpty) {
-      _text = '1:*';
-    } else {
-      _text = null;
-    }
+    _text = wasEmpty ? '1:*' : null;
   }
 
   /// Adds a user defined sequence of IDs
@@ -313,6 +337,7 @@ class MessageSequence {
     final sublist = _ids.sublist(start, end);
     final subsequence = MessageSequence(isUidSequence: isUidSequence);
     subsequence._ids.addAll(sublist);
+
     return subsequence;
   }
 
@@ -340,6 +365,7 @@ class MessageSequence {
     if (start < 0) {
       start = 0;
     }
+
     return subsequence(start, end);
   }
 
@@ -357,31 +383,41 @@ class MessageSequence {
   /// You must specify the number of existing messages with the [exists]
   /// parameter, in case this sequence contains the last element '*'
   /// in some form.
+  ///
   /// Use the [containsLast] method to determine if this sequence contains
   /// the last element '*'.
   List<int> toList([int? exists]) {
     if (exists == null && containsLast()) {
       throw InvalidArgumentException(
-          'Unable to list sequence when * is part of the list and the '
-          '\'exists\' parameter is not specified.');
+        'Unable to list sequence when * is part of the list and the '
+        '\'exists\' parameter is not specified.',
+      );
     }
     if (_isNilSequence) {
       throw InvalidArgumentException('Unable to list non existent sequence.');
     }
     final idSet = LinkedHashSet<int>.identity();
     if (_isAllAdded) {
-      for (var i = 1; i <= exists!; i++) {
+      if (exists == null) {
+        throw InvalidArgumentException(
+          'Unable to list sequence when * is part of the list and the '
+          '\'exists\' parameter is not specified.',
+        );
+      }
+      for (var i = 1; i <= exists; i++) {
         idSet.add(i);
       }
     } else {
       var index = 0;
       var zeroLoc = _ids.indexOf(_elementRangeStar, index);
       while (zeroLoc > 0) {
-        idSet
-          ..addAll(_ids.sublist(index, zeroLoc))
-          // Using a for-loop because we must generate a sequence when
-          //reaching the `STAR` value
-          ..addAll([for (var x = idSet.last + 1; x <= exists!; x++) x]);
+        idSet.addAll(_ids.sublist(index, zeroLoc));
+
+        // Using a for-loop because we must generate a sequence when
+        //reaching the `STAR` value
+        if (exists != null) {
+          idSet.addAll([for (var x = idSet.last + 1; x <= exists; x++) x]);
+        }
         index = zeroLoc + 1;
         zeroLoc = _ids.indexOf(_elementRangeStar, index);
       }
@@ -392,16 +428,19 @@ class MessageSequence {
     if (idSet.remove(_elementStar) && exists != null) {
       idSet.add(exists);
     }
+
     return idSet.toList();
   }
 
   @override
   String toString() {
-    if (_text != null) {
-      return _text!;
+    final text = _text;
+    if (text != null) {
+      return text;
     }
     final buffer = StringBuffer();
     render(buffer);
+
     return buffer.toString();
   }
 
@@ -409,10 +448,12 @@ class MessageSequence {
   void render(StringBuffer buffer) {
     if (_isNilSequence) {
       buffer.write('NIL');
+
       return;
     }
     if (_text != null) {
       buffer.write(_text);
+
       return;
     }
     if (isEmpty) {
@@ -497,7 +538,7 @@ enum SequenceNodeSelectionMode {
   firstLeaf,
 
   /// Only the last  / newest leaf of each nested 'thread'  is retrieved
-  lastLeaf
+  lastLeaf,
 }
 
 /// A message sequence to handle nested IDs like in the IMAP THREAD extension.
@@ -543,6 +584,7 @@ class SequenceNode {
   SequenceNode addChild(int childId) {
     final child = SequenceNode(childId, isUid: isUid);
     children.add(child);
+
     return child;
   }
 
@@ -576,6 +618,7 @@ class SequenceNode {
     } else {
       render(buffer);
     }
+
     return buffer.toString();
   }
 
@@ -592,6 +635,7 @@ class SequenceNode {
     assert(depth >= 1, 'depth must be at least 1 ($depth is invalid)');
     final root = SequenceNode.root(isUid: isUid);
     _flatten(depth, root);
+
     return root;
   }
 
@@ -620,15 +664,20 @@ class SequenceNode {
   /// Converts this node to a message sequence in the specified [mode].
   ///
   /// The [mode] defaults to all message IDs.
-  MessageSequence toMessageSequence(
-      {SequenceNodeSelectionMode mode = SequenceNodeSelectionMode.all}) {
+  MessageSequence toMessageSequence({
+    SequenceNodeSelectionMode mode = SequenceNodeSelectionMode.all,
+  }) {
     final sequence = MessageSequence(isUidSequence: isUid);
     _addToSequence(sequence, mode, 0);
+
     return sequence;
   }
 
   void _addToSequence(
-      MessageSequence sequence, SequenceNodeSelectionMode mode, int depth) {
+    MessageSequence sequence,
+    SequenceNodeSelectionMode mode,
+    int depth,
+  ) {
     if (mode == SequenceNodeSelectionMode.all || depth == 0) {
       if (hasId) {
         sequence.add(id);
@@ -694,8 +743,12 @@ class PagedMessageSequence {
   MessageSequence getCurrentPage() {
     assert(_currentPage > 0,
         'You have to call next() before you can access the first page.');
-    return sequence.subsequenceFromPage(_currentPage, pageSize,
-        skip: _addedIds);
+
+    return sequence.subsequenceFromPage(
+      _currentPage,
+      pageSize,
+      skip: _addedIds,
+    );
   }
 
   /// Advances this sequence to the next page and then returns
@@ -707,6 +760,7 @@ class PagedMessageSequence {
     assert(hasNext,
         'This paged sequence has no next page. Check hasNext property.');
     _currentPage++;
+
     return getCurrentPage();
   }
 
diff --git a/lib/src/imap/metadata.dart b/lib/src/imap/metadata.dart
index 46640f9c..d8950de5 100644
--- a/lib/src/imap/metadata.dart
+++ b/lib/src/imap/metadata.dart
@@ -63,6 +63,7 @@ class MetaDataEntry {
   /// Optional textual value
   String? get valueText {
     final value = this.value;
+
     return value == null ? null : String.fromCharCodes(value);
   }
 }
diff --git a/lib/src/imap/qresync.dart b/lib/src/imap/qresync.dart
index ba18b682..6b4ead9f 100644
--- a/lib/src/imap/qresync.dart
+++ b/lib/src/imap/qresync.dart
@@ -26,11 +26,14 @@ class QResyncParameters {
 
   /// Specifies the optional known message sequence IDs with [knownSequenceIds]
   /// along with their corresponding UIds [correspondingKnownUids].
-  void setKnownSequenceIdsWithTheirUids(MessageSequence knownSequenceIds,
-      MessageSequence correspondingKnownUids) {
+  void setKnownSequenceIdsWithTheirUids(
+    MessageSequence knownSequenceIds,
+    MessageSequence correspondingKnownUids,
+  ) {
     if (knownSequenceIds == correspondingKnownUids) {
       throw InvalidArgumentException(
-          'Invalid known and sequence ids are the same $knownSequenceIds');
+        'Invalid known and sequence ids are the same $knownSequenceIds',
+      );
     }
     _knownSequenceIds = knownSequenceIds;
     _knownSequenceIdsUids = correspondingKnownUids;
@@ -40,6 +43,7 @@ class QResyncParameters {
   String toString() {
     final buffer = StringBuffer();
     render(buffer);
+
     return buffer.toString();
   }
 
diff --git a/lib/src/imap/response.dart b/lib/src/imap/response.dart
index 12dbac94..af569a5d 100644
--- a/lib/src/imap/response.dart
+++ b/lib/src/imap/response.dart
@@ -60,6 +60,7 @@ class GenericImapResult {
         if (uidParts[1].isEmpty || uidParts[2].isEmpty) {
           return null;
         }
+
         return UidResponseCode(
           int.parse(uidParts[0]),
           MessageSequence.parse(uidParts[1], isUidSequence: true),
@@ -69,6 +70,7 @@ class GenericImapResult {
         if (uidParts[1].isEmpty) {
           return null;
         }
+
         return UidResponseCode(
           int.parse(uidParts[0]),
           null,
@@ -76,6 +78,7 @@ class GenericImapResult {
         );
       }
     }
+
     return null;
   }
 }
@@ -83,8 +86,11 @@ class GenericImapResult {
 /// Result for FETCH operations
 class FetchImapResult {
   /// Creates a new fetch result
-  const FetchImapResult(this.messages, this.vanishedMessagesUidSequence,
-      {this.modifiedSequence});
+  const FetchImapResult(
+    this.messages,
+    this.vanishedMessagesUidSequence, {
+    this.modifiedSequence,
+  });
 
   /// Any messages that have been removed by other clients.
   /// This is only given from QRESYNC compliant servers after having enabled
@@ -166,6 +172,7 @@ class SearchImapResult {
   /// Is this a partial search response?
   bool get isPartial {
     final partialRange = this.partialRange;
+
     return partialRange != null && partialRange.isNotEmpty;
   }
 }
@@ -174,7 +181,10 @@ class SearchImapResult {
 class UidResponseCode {
   /// Creates a new response code
   const UidResponseCode(
-      this.uidValidity, this.originalSequence, this.targetSequence);
+    this.uidValidity,
+    this.originalSequence,
+    this.targetSequence,
+  );
 
   /// The UID validity
   final int uidValidity;
@@ -261,6 +271,7 @@ class SortImapResult {
   /// Is this a partial response?
   bool get isPartial {
     final partialRange = this.partialRange;
+
     return partialRange != null && partialRange.isNotEmpty;
   }
 }
diff --git a/lib/src/imap/return_option.dart b/lib/src/imap/return_option.dart
index 02f3f1e5..2fcdfe1a 100644
--- a/lib/src/imap/return_option.dart
+++ b/lib/src/imap/return_option.dart
@@ -58,7 +58,8 @@ class ReturnOption {
     final parameters = this.parameters;
     if (parameters == null) {
       throw InvalidArgumentException(
-          '$name return option doesn\'t allow any parameter');
+        '$name return option doesn\'t allow any parameter',
+      );
     }
     if (isSingleParam && parameters.isNotEmpty) {
       parameters.replaceRange(0, 0, [parameter]);
@@ -73,11 +74,13 @@ class ReturnOption {
 
     if (parameters == null) {
       throw InvalidArgumentException(
-          '$name return option doesn\'t allow any parameter');
+        '$name return option doesn\'t allow any parameter',
+      );
     }
     if (isSingleParam && parameters.length > 1) {
       throw InvalidArgumentException(
-          '$name return options allows only one parameter');
+        '$name return options allows only one parameter',
+      );
     }
     parameters.addAll(parameters);
   }
@@ -102,6 +105,7 @@ class ReturnOption {
           ..write(')');
       }
     }
+
     return result.toString();
   }
 }
diff --git a/lib/src/mail/mail_account.dart b/lib/src/mail/mail_account.dart
index 9719b950..2e70053b 100644
--- a/lib/src/mail/mail_account.dart
+++ b/lib/src/mail/mail_account.dart
@@ -6,6 +6,7 @@ import 'package:json_annotation/json_annotation.dart';
 import '../discover/client_config.dart';
 import '../imap/imap_client.dart';
 import '../mail_address.dart';
+import '../private/util/non_nullable.dart';
 import 'mail_authentication.dart';
 
 part 'mail_account.g.dart';
@@ -26,41 +27,6 @@ class MailAccount {
     this.attributes = const {},
   });
 
-  /// Creates a mail account with  the given [name] for the specified [email]
-  /// from the discovered [config] with a a plain authentication for the
-  /// preferred incoming and preferred outgoing server.
-  ///
-  /// You nee to specify the [password].
-  ///
-  /// Specify the [userName] if it cannot be deducted from the email
-  /// or the discovery config.
-  ///
-  /// For SMTP usage you also should define the [outgoingClientDomain],
-  /// which defaults to `enough.de`.
-  factory MailAccount.fromDiscoveredSettings({
-    required String name,
-    required String email,
-    required String password,
-    required ClientConfig config,
-    required String userName,
-    String outgoingClientDomain = 'enough.de',
-    String? loginName,
-    bool supportsPlusAliases = false,
-    List<MailAddress> aliases = const [],
-  }) =>
-      MailAccount.fromDiscoveredSettingsWithAuth(
-        name: name,
-        email: email,
-        userName: userName,
-        auth: PlainAuthentication(
-            loginName ?? getLoginName(email, config.preferredIncomingServer!),
-            password),
-        config: config,
-        outgoingClientDomain: outgoingClientDomain,
-        supportsPlusAliases: supportsPlusAliases,
-        aliases: aliases,
-      );
-
   /// Creates a mail account with  the given [name] from the discovered [config]
   /// with the given [auth] for the preferred incoming and
   /// preferred outgoing server.
@@ -81,13 +47,18 @@ class MailAccount {
   }) {
     final incoming = MailServerConfig(
       authentication: auth,
-      serverConfig:
-          config.preferredIncomingImapServer ?? config.preferredIncomingServer!,
+      serverConfig: toValueOrThrow(
+        config.preferredIncomingImapServer ?? config.preferredIncomingServer,
+        'No incoming server found',
+      ),
     );
     final outgoing = MailServerConfig(
       authentication: outgoingAuth ?? auth,
-      serverConfig: config.preferredOutgoingServer!,
+      serverConfig: config.preferredOutgoingServer.toValueOrThrow(
+        'No outgoing server found',
+      ),
     );
+
     return MailAccount(
       name: name,
       email: email,
@@ -209,6 +180,7 @@ class MailAccount {
         usernameType: UsernameType.unknown,
       ),
     );
+
     return MailAccount(
       name: name,
       email: email,
@@ -225,12 +197,55 @@ class MailAccount {
   factory MailAccount.fromJson(Map<String, dynamic> json) =>
       _$MailAccountFromJson(json);
 
+  /// Creates a mail account with  the given [name] for the specified [email]
+  /// from the discovered [config] with a a plain authentication for the
+  /// preferred incoming and preferred outgoing server.
+  ///
+  /// You nee to specify the [password].
+  ///
+  /// Specify the [userName] if it cannot be deducted from the email
+  /// or the discovery config.
+  ///
+  /// For SMTP usage you also should define the [outgoingClientDomain],
+  /// which defaults to `enough.de`.
+  factory MailAccount.fromDiscoveredSettings({
+    required String name,
+    required String email,
+    required String password,
+    required ClientConfig config,
+    required String userName,
+    String outgoingClientDomain = 'enough.de',
+    String? loginName,
+    bool supportsPlusAliases = false,
+    List<MailAddress> aliases = const [],
+  }) =>
+      MailAccount.fromDiscoveredSettingsWithAuth(
+        name: name,
+        email: email,
+        userName: userName,
+        auth: PlainAuthentication(
+          loginName ??
+              getLoginName(
+                email,
+                config.preferredIncomingServer.toValueOrThrow(
+                  'no preferred incoming server found',
+                ),
+              ),
+          password,
+        ),
+        config: config,
+        outgoingClientDomain: outgoingClientDomain,
+        supportsPlusAliases: supportsPlusAliases,
+        aliases: aliases,
+      );
+
   /// Generates JSON from this [MailAccount]
   Map<String, dynamic> toJson() => _$MailAccountToJson(this);
 
   /// The name of the account
   final String name;
 
+  // cSpell: ignore Ghez
   /// The associated name of the user such as `First Last`, e.g. `Andrea Ghez`
   final String userName;
 
@@ -351,6 +366,7 @@ class MailAccount {
     if (outgoingAuth is UserNameBasedAuthentication) {
       outgoingAuth = outgoingAuth.copyWithUserName(authenticationUserName);
     }
+
     return copyWith(
       incoming: incoming.copyWith(authentication: incomingAuth),
       outgoing: outgoing.copyWith(authentication: outgoingAuth),
diff --git a/lib/src/mail/mail_authentication.dart b/lib/src/mail/mail_authentication.dart
index c4f9834b..c622ca57 100644
--- a/lib/src/mail/mail_authentication.dart
+++ b/lib/src/mail/mail_authentication.dart
@@ -6,6 +6,7 @@ import '../discover/client_config.dart';
 import '../exception.dart';
 import '../imap/imap_client.dart';
 import '../pop/pop_client.dart';
+import '../private/util/non_nullable.dart';
 import '../smtp/smtp_client.dart';
 
 part 'mail_authentication.g.dart';
@@ -27,7 +28,8 @@ abstract class MailAuthentication {
         return OauthAuthentication.fromJson(json);
     }
     throw InvalidArgumentException(
-        'unsupported MailAuthentication type [$authentication]');
+      'unsupported MailAuthentication type [$authentication]',
+    );
   }
 
   /// Converts this [MailAuthentication] to JSON
@@ -81,19 +83,26 @@ class PlainAuthentication extends UserNameBasedAuthentication {
   final String password;
 
   @override
-  Future<void> authenticate(ServerConfig serverConfig,
-      {ImapClient? imap, PopClient? pop, SmtpClient? smtp}) async {
+  Future<void> authenticate(
+    ServerConfig serverConfig, {
+    ImapClient? imap,
+    PopClient? pop,
+    SmtpClient? smtp,
+  }) async {
     final name = userName;
     final pwd = password;
     switch (serverConfig.type) {
       case ServerType.imap:
-        await imap!.login(name, pwd);
+        await imap.toValueOrThrow('no [ImapClient] found').login(name, pwd);
         break;
       case ServerType.pop:
-        await pop!.login(name, pwd);
+        await pop.toValueOrThrow('no [PopClient] found').login(name, pwd);
         break;
       case ServerType.smtp:
-        final authMechanism = smtp!.serverInfo.supportsAuth(AuthMechanism.plain)
+        if (smtp == null) {
+          throw ArgumentError('no [SmtpClient] found');
+        }
+        final authMechanism = smtp.serverInfo.supportsAuth(AuthMechanism.plain)
             ? AuthMechanism.plain
             : smtp.serverInfo.supportsAuth(AuthMechanism.login)
                 ? AuthMechanism.login
@@ -102,7 +111,8 @@ class PlainAuthentication extends UserNameBasedAuthentication {
         break;
       default:
         throw InvalidArgumentException(
-            'Unknown server type ${serverConfig.typeName}');
+          'Unknown server type ${serverConfig.typeName}',
+        );
     }
   }
 
@@ -252,6 +262,7 @@ class OauthAuthentication extends UserNameBasedAuthentication {
     String? provider,
   }) {
     final token = OauthToken.fromText(oauthTokenText, provider: provider);
+
     return OauthAuthentication(userName, token);
   }
 
@@ -274,17 +285,24 @@ class OauthAuthentication extends UserNameBasedAuthentication {
     final accessToken = token.accessToken;
     switch (serverConfig.type) {
       case ServerType.imap:
-        await imap!.authenticateWithOAuth2(userName, accessToken);
+        await imap
+            .toValueOrThrow('no [ImapClient] found')
+            .authenticateWithOAuth2(userName, accessToken);
         break;
       case ServerType.pop:
-        await pop!.login(userName, accessToken);
+        await pop
+            .toValueOrThrow('no [PopClient] found')
+            .login(userName, accessToken);
         break;
       case ServerType.smtp:
-        await smtp!.authenticate(userName, accessToken, AuthMechanism.xoauth2);
+        await smtp
+            .toValueOrThrow('no [SmtpClient] found')
+            .authenticate(userName, accessToken, AuthMechanism.xoauth2);
         break;
       default:
         throw InvalidArgumentException(
-            'Unknown server type ${serverConfig.typeName}');
+          'Unknown server type ${serverConfig.typeName}',
+        );
     }
   }
 
diff --git a/lib/src/mail/mail_client.dart b/lib/src/mail/mail_client.dart
index ec17c4c0..6596d5fb 100644
--- a/lib/src/mail/mail_client.dart
+++ b/lib/src/mail/mail_client.dart
@@ -8,6 +8,7 @@ import 'package:synchronized/synchronized.dart';
 
 import '../../enough_mail.dart';
 import '../private/util/client_base.dart';
+import '../private/util/non_nullable.dart';
 
 /// Definition for optional event filters, compare [MailClient.addEventFilter].
 typedef MailEventFilter = bool Function(MailEvent event);
@@ -249,7 +250,7 @@ class MailClient {
   /// Compare [eventBus].
   void addEventFilter(MailEventFilter filter) {
     _eventFilters ??= <MailEventFilter>[];
-    _eventFilters!.add(filter);
+    _eventFilters?.add(filter);
   }
 
   /// Removes the specified mail event [filter].
@@ -419,8 +420,11 @@ class MailClient {
     final tree = Tree<Mailbox?>(null)
       ..populateFromList(
         boxes,
-        (child) => child!.getParent(boxes, separator,
-            createIntermediate: createIntermediate),
+        (child) => child?.getParent(
+          boxes,
+          separator,
+          createIntermediate: createIntermediate,
+        ),
       );
     final parent = tree.root;
     final children = parent.children;
@@ -434,7 +438,7 @@ class MailClient {
         } else {
           element = TreeElement<Mailbox?>(box, parent);
         }
-        children!.insert(0, element);
+        children?.insert(0, element);
       }
     }
 
@@ -447,13 +451,13 @@ class MailClient {
   ) {
     if (root.value == mailbox) {
       if ((root.children?.isEmpty ?? true) && (root.parent != null)) {
-        root.parent!.children!.remove(root);
+        root.parent?.children?.remove(root);
       }
 
       return root as TreeElement<Mailbox?>?;
     }
     if (root.children != null) {
-      for (final child in root.children!) {
+      for (final child in root.children ?? []) {
         final element = _extractTreeElementWithoutChildren(child, mailbox);
         if (element != null) {
           return element;
@@ -2278,7 +2282,9 @@ class _IncomingImapClient extends _IncomingMailClient {
         if (uid != null) {
           smallMessagesSequenceUids.add(uid);
         } else {
-          smallMessagesSequenceSequenceIds.add(msg.sequenceId!);
+          smallMessagesSequenceSequenceIds.add(
+            msg.sequenceId.toValueOrThrow('no sequenceId found in msg'),
+          );
         }
       }
       if (smallMessagesSequenceUids.isNotEmpty) {
@@ -2304,8 +2310,8 @@ class _IncomingImapClient extends _IncomingMailClient {
     if (threadData != null) {
       fetchImapResult.messages.forEach(threadData.setThreadSequence);
     }
-    fetchImapResult.messages
-        .sort((msg1, msg2) => msg1.sequenceId!.compareTo(msg2.sequenceId!));
+    fetchImapResult.messages.sort(
+        (msg1, msg2) => (msg1.sequenceId ?? 0).compareTo(msg2.sequenceId ?? 0));
     final email = mailClient._account.email;
     final encodedMailboxName = _selectedMailbox?.encodedName ?? '';
     final mailboxUidValidity = _selectedMailbox?.uidValidity ?? 0;
@@ -2358,7 +2364,7 @@ class _IncomingImapClient extends _IncomingMailClient {
         );
       } else {
         fetchImapResult = await _imapClient.fetchMessage(
-          message.sequenceId!,
+          message.sequenceId.toValueOrThrow('no sequenceId found in msg'),
           '(BODY[$fetchId])',
           responseTimeout: responseTimeout,
         );
@@ -2367,14 +2373,18 @@ class _IncomingImapClient extends _IncomingMailClient {
         final part = fetchImapResult.messages.first.getPart(fetchId);
         if (part == null) {
           throw MailException(
-              mailClient, 'Unable to fetch message part <$fetchId>');
+            mailClient,
+            'Unable to fetch message part <$fetchId>',
+          );
         }
         message.setPart(fetchId, part);
 
         return part;
       } else {
         throw MailException(
-            mailClient, 'Unable to fetch message part <$fetchId>');
+          mailClient,
+          'Unable to fetch message part <$fetchId>',
+        );
       }
     } on ImapException catch (e) {
       throw MailException.fromImap(mailClient, e);
@@ -2570,7 +2580,7 @@ class _IncomingImapClient extends _IncomingMailClient {
           // flags information etc is being kept:
           message
             ..body = body
-            ..envelope ??= result.envelope!
+            ..envelope ??= result.envelope
             ..headers = result.headers
             ..copyIndividualParts(result)
             ..flags = result.flags;
@@ -2578,6 +2588,7 @@ class _IncomingImapClient extends _IncomingMailClient {
           if (threadData != null) {
             threadData.setThreadSequence(message);
           }
+
           return message;
         }
       } on ImapException catch (e, s) {
@@ -2693,18 +2704,22 @@ class _IncomingImapClient extends _IncomingMailClient {
         try {
           await _pauseIdle();
           await _imapClient.closeMailbox();
-          await _imapClient.selectMailbox(deleteResult.targetMailbox!);
+          await _imapClient.selectMailbox(
+            deleteResult.targetMailbox.toValueOrThrow('no targetMailbox found'),
+          );
 
           GenericImapResult? result;
           final targetSequence = deleteResult.targetSequence;
           if (targetSequence != null) {
-            if (targetSequence.isUidSequence) {
-              result = await _imapClient.uidMove(targetSequence,
-                  targetMailbox: deleteResult.originalMailbox);
-            } else {
-              result = await _imapClient.move(targetSequence,
-                  targetMailbox: deleteResult.originalMailbox);
-            }
+            result = targetSequence.isUidSequence
+                ? await _imapClient.uidMove(
+                    targetSequence,
+                    targetMailbox: deleteResult.originalMailbox,
+                  )
+                : await _imapClient.move(
+                    targetSequence,
+                    targetMailbox: deleteResult.originalMailbox,
+                  );
           }
           await _imapClient.closeMailbox();
           await _imapClient.selectMailbox(deleteResult.originalMailbox);
@@ -2728,12 +2743,16 @@ class _IncomingImapClient extends _IncomingMailClient {
           await _pauseIdle();
           if (deleteResult.originalSequence.isUidSequence) {
             await _imapClient.uidStore(
-                deleteResult.originalSequence, [MessageFlags.deleted],
-                action: StoreAction.remove);
+              deleteResult.originalSequence,
+              [MessageFlags.deleted],
+              action: StoreAction.remove,
+            );
           } else {
             await _imapClient.store(
-                deleteResult.originalSequence, [MessageFlags.deleted],
-                action: StoreAction.remove);
+              deleteResult.originalSequence,
+              [MessageFlags.deleted],
+              action: StoreAction.remove,
+            );
           }
           final targetMailbox = deleteResult.targetMailbox;
           final targetSequence = deleteResult.targetSequence;
@@ -2741,12 +2760,18 @@ class _IncomingImapClient extends _IncomingMailClient {
             await _imapClient.closeMailbox();
             await _imapClient.selectMailbox(targetMailbox);
 
-            if (deleteResult.targetSequence!.isUidSequence) {
-              await _imapClient.uidStore(targetSequence, [MessageFlags.deleted],
-                  action: StoreAction.add);
+            if (targetSequence.isUidSequence) {
+              await _imapClient.uidStore(
+                targetSequence,
+                [MessageFlags.deleted],
+                action: StoreAction.add,
+              );
             } else {
-              await _imapClient.store(targetSequence, [MessageFlags.deleted],
-                  action: StoreAction.add);
+              await _imapClient.store(
+                targetSequence,
+                [MessageFlags.deleted],
+                action: StoreAction.add,
+              );
             }
 
             await _imapClient.closeMailbox();
@@ -2760,8 +2785,10 @@ class _IncomingImapClient extends _IncomingMailClient {
         break;
       case DeleteAction.pop:
         throw InvalidArgumentException(
-            'POP delete action not expected for IMAP connection.');
+          'POP delete action not expected for IMAP connection.',
+        );
     }
+
     return deleteResult.reverse();
   }
 
@@ -2779,50 +2806,55 @@ class _IncomingImapClient extends _IncomingMailClient {
         await _imapClient.selectMailbox(mailbox);
       }
       await _imapClient.markDeleted(sequence, silent: true);
-      if (expunge == true) {
+      if (expunge) {
         canUndo = false;
         await _imapClient.expunge();
       }
-      if (selectedMailbox != mailbox) {
-        await _imapClient.selectMailbox(selectedMailbox!);
+      if (selectedMailbox != null && selectedMailbox != mailbox) {
+        await _imapClient.selectMailbox(selectedMailbox);
       }
     } on ImapException catch (e) {
       throw MailException.fromImap(mailClient, e);
     } finally {
       await _resumeIdle();
     }
+
     return DeleteResult(
-        DeleteAction.flag, sequence, mailbox, null, null, mailClient,
-        canUndo: canUndo);
+      DeleteAction.flag,
+      sequence,
+      mailbox,
+      null,
+      null,
+      mailClient,
+      canUndo: canUndo,
+    );
   }
 
   Future<MoveResult> _moveMessages(
-    MessageSequence? sequence,
+    MessageSequence sequence,
     Mailbox? target, {
     List<MimeMessage>? messages,
   }) async {
     final sourceMailbox = _selectedMailbox;
     if (sourceMailbox == null) {
       throw MailException(
-          mailClient, 'Unable to move messages without selected mailbox');
+        mailClient,
+        'Unable to move messages without selected mailbox',
+      );
     }
     MoveAction moveAction;
-    GenericImapResult imapResult;
+    final GenericImapResult imapResult;
     if (_imapClient.serverInfo.supports(ImapServerInfo.capabilityMove)) {
       moveAction = MoveAction.move;
-      if (sequence!.isUidSequence) {
-        imapResult = await _imapClient.uidMove(sequence, targetMailbox: target);
-      } else {
-        imapResult = await _imapClient.move(sequence, targetMailbox: target);
-      }
+      imapResult = sequence.isUidSequence
+          ? await _imapClient.uidMove(sequence, targetMailbox: target)
+          : await _imapClient.move(sequence, targetMailbox: target);
     } else {
       moveAction = MoveAction.copy;
 
-      if (sequence!.isUidSequence) {
-        imapResult = await _imapClient.uidCopy(sequence, targetMailbox: target);
-      } else {
-        imapResult = await _imapClient.copy(sequence, targetMailbox: target);
-      }
+      imapResult = sequence.isUidSequence
+          ? await _imapClient.uidCopy(sequence, targetMailbox: target)
+          : await _imapClient.copy(sequence, targetMailbox: target);
       await _imapClient.store(
         sequence,
         [MessageFlags.deleted],
@@ -2833,6 +2865,7 @@ class _IncomingImapClient extends _IncomingMailClient {
     final targetSequence = imapResult.responseCodeCopyUid?.targetSequence;
     // copy and move commands result in a mapping sequence
     // which is relevant for undo operations:
+
     return MoveResult(
       moveAction,
       sequence,
@@ -2858,6 +2891,7 @@ class _IncomingImapClient extends _IncomingMailClient {
         target,
         messages: messages,
       );
+
       return response;
     } on ImapException catch (e) {
       throw MailException.fromImap(mailClient, e);
@@ -2870,13 +2904,16 @@ class _IncomingImapClient extends _IncomingMailClient {
   Future<MoveResult> undoMove(MoveResult moveResult) async {
     try {
       await _pauseIdle();
-      await _imapClient.selectMailbox(moveResult.targetMailbox!);
+      await _imapClient.selectMailbox(
+        moveResult.targetMailbox.toValueOrThrow('no targetMailbox found'),
+      );
       final response = await _moveMessages(
-        moveResult.targetSequence,
+        moveResult.targetSequence.toValueOrThrow('no targetSequence found'),
         moveResult.originalMailbox,
         messages: moveResult.messages,
       );
       await _imapClient.selectMailbox(moveResult.originalMailbox);
+
       return response;
     } on ImapException catch (e) {
       throw MailException.fromImap(mailClient, e);
@@ -2915,8 +2952,12 @@ class _IncomingImapClient extends _IncomingMailClient {
       }
 
       final requestSequence = sequence.subsequenceFromPage(1, search.pageSize);
-      final messages = await _fetchMessageSequence(requestSequence,
-          fetchPreference: search.fetchPreference, markAsSeen: false);
+      final messages = await _fetchMessageSequence(
+        requestSequence,
+        fetchPreference: search.fetchPreference,
+        markAsSeen: false,
+      );
+
       return MailSearchResult(
         search,
         PagedMessageSequence(sequence, pageSize: search.pageSize),
@@ -2926,9 +2967,10 @@ class _IncomingImapClient extends _IncomingMailClient {
     } on ImapException catch (e, s) {
       if (search.queryType == SearchQueryType.allTextHeaders) {
         resumeIdleInFinally = false;
-        final orSearch = _selectedMailbox!.isSent
+        final orSearch = _selectedMailbox?.isSent ?? false
             ? SearchQueryType.toOrSubject
             : SearchQueryType.fromOrSubject;
+
         return searchMessages(search.copyWith(queryType: orSearch));
       }
       throw MailException.fromImap(mailClient, e, s);
@@ -3158,12 +3200,14 @@ class _IncomingPopClient extends _IncomingMailClient {
     final status = await _popClient.status();
     mailbox.messagesExists = status.numberOfMessages;
     _selectedMailbox = mailbox;
+
     return mailbox;
   }
 
   @override
   Future<List<MimeMessage>> poll() async {
-    final numberOfKNownMessages = _selectedMailbox!.messagesExists;
+    final numberOfKNownMessages =
+        _selectedMailbox.toValueOrThrow('no mailbox selected').messagesExists;
     // in POP3 a new session is required to get a new status
     await connect();
     final status = await _popClient.status();
@@ -3223,7 +3267,8 @@ class _IncomingPopClient extends _IncomingMailClient {
     Duration? responseTimeout,
   }) {
     throw InvalidArgumentException(
-        'POP does not support fetching message parts.');
+      'POP does not support fetching message parts.',
+    );
   }
 
   @override
@@ -3234,8 +3279,9 @@ class _IncomingPopClient extends _IncomingMailClient {
     List<MediaToptype>? includedInlineTypes,
     Duration? responseTimeout,
   }) async {
-    final id = message.sequenceId!;
+    final id = message.sequenceId.toValueOrThrow('no sequenceId found');
     final messageResponse = await _popClient.retrieve(id);
+
     return messageResponse;
   }
 
@@ -3270,13 +3316,13 @@ class _IncomingPopClient extends _IncomingMailClient {
   @override
   Future<DeleteResult> deleteAllMessages(Mailbox mailbox,
       {bool expunge = false}) {
-    // TODO: implement deleteAllMessages
+    // TODO(RV): implement deleteAllMessages
     throw UnimplementedError();
   }
 
   @override
   Future<DeleteResult> undoDeleteMessages(DeleteResult deleteResult) {
-    // TODO: implement undoDeleteMessages
+    // TODO(RV): implement undoDeleteMessages
     throw UnimplementedError();
   }
 
@@ -3286,26 +3332,26 @@ class _IncomingPopClient extends _IncomingMailClient {
     Mailbox target, {
     List<MimeMessage>? messages,
   }) {
-    // TODO: implement moveMessages
+    // TODO(RV): implement moveMessages
     throw UnimplementedError();
   }
 
   @override
   Future<MoveResult> undoMove(MoveResult moveResult) {
-    // TODO: implement undoMove
+    // TODO(RV): implement undoMove
     throw UnimplementedError();
   }
 
   @override
   Future<MailSearchResult> searchMessages(MailSearch search) {
-    // TODO: implement searchMessages
+    // TODO(RV): implement searchMessages
     throw UnimplementedError();
   }
 
   @override
   Future<UidResponseCode?> appendMessage(
       MimeMessage message, Mailbox targetMailbox, List<String>? flags) {
-    // TODO: implement appendMessage
+    // TODO(RV): implement appendMessage
     throw UnimplementedError();
   }
 
@@ -3327,7 +3373,7 @@ class _IncomingPopClient extends _IncomingMailClient {
     int pageSize, {
     Duration? responseTimeout,
   }) {
-    // TODO: implement fetchThreads
+    // TODO(RV): implement fetchThreads
     throw UnimplementedError();
   }
 
@@ -3337,13 +3383,13 @@ class _IncomingPopClient extends _IncomingMailClient {
   @override
   Future<ThreadDataResult> fetchThreadData(Mailbox mailbox, DateTime since,
       {required bool setThreadSequences}) {
-    // TODO: implement fetchThreadData
+    // TODO(RV): implement fetchThreadData
     throw UnimplementedError();
   }
 
   @override
   Future<Mailbox> createMailbox(String mailboxName, {Mailbox? parentMailbox}) {
-    // TODO: implement createMailbox
+    // TODO(RV): implement createMailbox
     throw UnimplementedError();
   }
 
@@ -3352,7 +3398,7 @@ class _IncomingPopClient extends _IncomingMailClient {
 
   @override
   Future<void> deleteMailbox(Mailbox mailbox) {
-    // TODO: implement deleteMailbox
+    // TODO(RV): implement deleteMailbox
     throw UnimplementedError();
   }
 
diff --git a/lib/src/message_builder.dart b/lib/src/message_builder.dart
index 3e39f8bc..efd64125 100644
--- a/lib/src/message_builder.dart
+++ b/lib/src/message_builder.dart
@@ -241,14 +241,8 @@ class PartBuilder {
       ..contentDisposition = disposition
       ..text = text;
     if (disposition?.disposition == ContentDisposition.attachment) {
-      final info = AttachmentInfo(
-          null,
-          mediaType,
-          disposition!.filename,
-          disposition.size,
-          disposition.disposition,
-          utf8.encode(text) as Uint8List,
-          child);
+      final info = AttachmentInfo(null, mediaType, disposition!.filename,
+          disposition.size, disposition.disposition, utf8.encode(text), child);
       _attachments.add(info);
     }
     return child;
@@ -458,6 +452,7 @@ class PartBuilder {
       MailCodec.base64.encodeData(data),
       containsHeader: false,
     );
+
     return child;
   }
 
@@ -484,9 +479,10 @@ class PartBuilder {
     if (disposition == ContentDisposition.attachment) {
       _attachments.add(
         AttachmentInfo(null, mediaType, filename, null, disposition,
-            utf8.encode(messageText) as Uint8List, partBuilder),
+            utf8.encode(messageText), partBuilder),
       );
     }
+
     return partBuilder;
   }
 
@@ -505,6 +501,7 @@ class PartBuilder {
         ..addTextPlain(plainText)
         ..addTextHtml(htmlText);
     }
+
     return partBuilder;
   }
 
@@ -526,8 +523,11 @@ class PartBuilder {
   /// Compare [MailConventions] for common header names.
   /// Set [encoding] to any of the [HeaderEncoding] formats to
   /// encode the header.
-  void setHeader(String name, String? value,
-      {HeaderEncoding encoding = HeaderEncoding.none}) {
+  void setHeader(
+    String name,
+    String? value, {
+    HeaderEncoding encoding = HeaderEncoding.none,
+  }) {
     _part.setHeader(name, value, encoding);
   }
 
@@ -761,6 +761,7 @@ class MessageBuilder extends PartBuilder {
         ..addTextPlain(plainText)
         ..addTextHtml(htmlText);
     }
+
     return builder;
   }
 
@@ -771,8 +772,9 @@ class MessageBuilder extends PartBuilder {
   ///
   /// You can also create a new MessageBuilder and call [setContentType]
   /// with the same effect when using the multipart/mixed media subtype.
-  factory MessageBuilder.prepareMultipartMixedMessage(
-          {TransferEncoding transferEncoding = TransferEncoding.eightBit}) =>
+  factory MessageBuilder.prepareMultipartMixedMessage({
+    TransferEncoding transferEncoding = TransferEncoding.eightBit,
+  }) =>
       MessageBuilder.prepareMessageWithMediaType(MediaSubtype.multipartMixed,
           transferEncoding: transferEncoding);
 
@@ -783,12 +785,15 @@ class MessageBuilder extends PartBuilder {
   ///
   /// You can also create a new MessageBuilder and call [setContentType]
   /// with the same effect when using the identical media subtype.
-  factory MessageBuilder.prepareMessageWithMediaType(MediaSubtype subtype,
-      {TransferEncoding transferEncoding = TransferEncoding.eightBit}) {
+  factory MessageBuilder.prepareMessageWithMediaType(
+    MediaSubtype subtype, {
+    TransferEncoding transferEncoding = TransferEncoding.eightBit,
+  }) {
     final mediaType = subtype.mediaType;
     final builder = MessageBuilder()
       ..setContentType(mediaType)
       ..transferEncoding = transferEncoding;
+
     return builder;
   }
 
@@ -805,7 +810,9 @@ class MessageBuilder extends PartBuilder {
   /// * `in-reply-to` -  message ID to which the new message is a reply
   /// ```
   factory MessageBuilder.prepareMailtoBasedMessage(
-      Uri mailto, MailAddress from) {
+    Uri mailto,
+    MailAddress from,
+  ) {
     final builder = MessageBuilder()
       ..from = [from]
       ..setContentType(MediaType.textPlain, characterSet: CharacterSet.utf8)
@@ -843,6 +850,7 @@ class MessageBuilder extends PartBuilder {
       }
     }
     builder.to = to;
+
     return builder;
   }
 
@@ -851,6 +859,7 @@ class MessageBuilder extends PartBuilder {
     final builder = MessageBuilder()
       ..originalMessage = draft
       .._copy(draft);
+
     return builder;
   }
 
@@ -1103,7 +1112,8 @@ class MessageBuilder extends PartBuilder {
     recipient ??= (from?.isNotEmpty ?? false) ? from!.first : null;
     if (recipient == null) {
       throw InvalidArgumentException(
-          'Either define a sender in from or specify the recipient parameter');
+        'Either define a sender in from or specify the recipient parameter',
+      );
     }
     setHeader(MailConventions.headerDispositionNotificationTo, recipient.email);
   }
@@ -1179,6 +1189,7 @@ class MessageBuilder extends PartBuilder {
     }
     _buildPart();
     _message.parse();
+
     return _message;
   }
 
@@ -1355,6 +1366,7 @@ class MessageBuilder extends PartBuilder {
     }
     mdnPart.text = buffer.toString();
     builder.from = [finalRecipient];
+
     return builder.buildMimeMessage();
   }
 
@@ -1395,6 +1407,7 @@ class MessageBuilder extends PartBuilder {
     } else {
       id = '<$random@$hostName>';
     }
+
     return id;
   }
 
@@ -1490,6 +1503,7 @@ class MessageBuilder extends PartBuilder {
       case 'base64':
         return TransferEncoding.base64;
     }
+
     return TransferEncoding.automatic;
   }
 
@@ -1545,6 +1559,7 @@ class MessageBuilder extends PartBuilder {
         }
       }
     }
+
     return '$defaultAbbreviation: $originalSubject';
   }
 
@@ -1566,6 +1581,7 @@ class MessageBuilder extends PartBuilder {
       final rune = characterRunes.elementAt(charIndex);
       buffer.writeCharCode(rune);
     }
+
     return buffer.toString();
   }
 
@@ -1645,6 +1661,7 @@ class MessageBuilder extends PartBuilder {
       }
       result = result.replaceAll(sequence, replacement);
     }
+
     return result;
   }
 
@@ -1658,6 +1675,7 @@ class MessageBuilder extends PartBuilder {
       address.writeToStringBuffer(buffer);
       addDelimiter = true;
     }
+
     return buffer.toString();
   }
 }
diff --git a/lib/src/private/util/non_nullable.dart b/lib/src/private/util/non_nullable.dart
new file mode 100644
index 00000000..ed9b0cda
--- /dev/null
+++ b/lib/src/private/util/non_nullable.dart
@@ -0,0 +1,22 @@
+/// Extracts the value or throws an [ArgumentError] if the value is `null`.
+T toValueOrThrow<T>(
+  T? value,
+  String reason,
+) =>
+    value.toValueOrThrow(reason);
+
+/// Allows to extract the non-nullable value or throws an [ArgumentError] if the
+/// value is `null`.
+extension ValueExtension<T> on T? {
+  /// Extracts the value or throws an [ArgumentError] if the value is `null`.
+  T toValueOrThrow(
+    String reason,
+  ) {
+    final value = this;
+    if (value == null) {
+      throw ArgumentError(reason);
+    }
+
+    return value;
+  }
+}
diff --git a/pubspec.yaml b/pubspec.yaml
index 2de4da3f..25a5c7f6 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -4,6 +4,13 @@ description: IMAP, POP3 and SMTP for email developers. Choose between a low
   Discover email settings.
 version: 2.1.6
 homepage: https://github.com/Enough-Software/enough_mail
+topics:
+  - email
+  - imap
+  - pop3
+  - smtp
+  - mime
+
 
 environment:
   sdk: '>=2.19.0 <4.0.0'
@@ -21,8 +28,13 @@ dependencies:
   synchronized: ^3.1.0
   xml: ">=6.0.0 <7.0.0"
 
+dependency_overrides:
+  http: ^1.1.0 # for dart_code_metrics
+
 dev_dependencies:
   build_runner: ^2.3.0
+  dart_code_metrics: 5.7.6
+  flutter_lints: ^3.0.0
   json_serializable: ^6.3.0
   lints: ^3.0.0
   test: ^1.20.1