Fix issue sending unicode messages in Python 3

Connection.send() now uses email.message.Message.as_bytes() in Python 3, and email.message.Message.as_string() in Python 2.

flask_mail.py

@@ -183,7 +183,7 @@ def send(self, message, envelope_from=None):
         if self.host:
             self.host.sendmail(sanitize_address(envelope_from or message.sender),
                                list(sanitize_addresses(message.send_to)),
-                               message.as_string(),
+                               message.as_bytes() if PY3 else message.as_string(),
                                message.mail_options,
                                message.rcpt_options)
 
@@ -298,7 +298,7 @@ def _mimetext(self, text, subtype='plain'):
         charset = self.charset or 'utf-8'
         return MIMEText(text, _subtype=subtype, _charset=charset)
 
-    def as_string(self):
+    def _message(self):
         """Creates the email"""
 
         encoding = self.charset or 'utf-8'
@@ -364,11 +364,20 @@ def as_string(self):
         if message_policy:
             msg.policy = message_policy
 
-        return msg.as_string()
+        return msg
+
+    def as_string(self):
+        return self._message().as_string()
+
+    def as_bytes(self):
+        return self._message().as_bytes()
 
     def __str__(self):
         return self.as_string()
 
+    def __bytes__(self):
+        return self.as_bytes()
+
     def has_bad_headers(self):
         """Checks for bad headers i.e. newlines in subject, sender or recipients.
         RFC5322: Allows multiline CRLF with trailing whitespace (FWS) in headers

tests.py

@@ -13,7 +13,7 @@
 from email import charset
 
 from flask import Flask
-from flask_mail import Mail, Message, BadHeaderError, sanitize_address
+from flask_mail import Mail, Message, BadHeaderError, sanitize_address, PY3
 from speaklater import make_lazy_string
 
 
@@ -597,10 +597,11 @@ def test_sendmail_with_ascii_recipient(self):
                               recipients=["to@example.com"],
                               body="testing")
                 conn.send(msg)
+
                 host.sendmail.assert_called_once_with(
                     "from@example.com",
                     ["to@example.com"],
-                    msg.as_string(),
+                    msg.as_bytes() if PY3 else msg.as_string(),
                     msg.mail_options,
                     msg.rcpt_options
                 )
@@ -613,10 +614,46 @@ def test_sendmail_with_non_ascii_recipient(self):
                               recipients=[u'ÄÜÖ → ✓ <to@example.com>'],
                               body="testing")
                 conn.send(msg)
+
                 host.sendmail.assert_called_once_with(
                     "from@example.com",
                     ["=?utf-8?b?w4TDnMOWIOKGkiDinJM=?= <to@example.com>"],
-                    msg.as_string(),
+                    msg.as_bytes() if PY3 else msg.as_string(),
+                    msg.mail_options,
+                    msg.rcpt_options
+                )
+
+    def test_sendmail_with_ascii_body(self):
+        with self.mail.connect() as conn:
+            with mock.patch.object(conn, 'host') as host:
+                msg = Message(subject="testing",
+                              sender="from@example.com",
+                              recipients=["to@example.com"],
+                              body="body")
+                conn.send(msg)
+
+                host.sendmail.assert_called_once_with(
+                    "from@example.com",
+                    ["to@example.com"],
+                    msg.as_bytes() if PY3 else msg.as_string(),
+                    msg.mail_options,
+                    msg.rcpt_options
+                )
+
+    def test_sendmail_with_non_ascii_body(self):
+        with self.mail.connect() as conn:
+            with mock.patch.object(conn, 'host') as host:
+                msg = Message(subject="testing",
+                              sender="from@example.com",
+                              recipients=["to@example.com"],
+                              body=u"Öö")
+
+                conn.send(msg)
+
+                host.sendmail.assert_called_once_with(
+                    "from@example.com",
+                    ["to@example.com"],
+                    msg.as_bytes() if PY3 else msg.as_string(),
                     msg.mail_options,
                     msg.rcpt_options
                 )