Check Invalid Email Token

packages/syft/src/syft/service/notifier/notifier.py

@@ -48,6 +48,26 @@ def __init__(
             smtp_server=self.server, smtp_port=587, access_token=self.token
         )
 
+    @staticmethod
+    def check_credentials(
+        server: str,
+        port: int,
+        token: Optional[str] = None,
+        username: Optional[str] = None,
+        password: Optional[str] = None,
+    ) -> bool:
+        if token:
+            return SMTPClient(
+                smtp_server=server, smtp_port=port, access_token=token
+            ).check_credentials()
+        else:
+            return SMTPClient(
+                smtp_server=server,
+                smtp_port=port,
+                username=username,
+                password=password,
+            ).check_credentials()
+
     def send(self, node: AbstractNode, notification: Notification) -> Result[Ok, Err]:
         try:
             user_service = node.get_service("userservice")
@@ -118,6 +138,11 @@ def slack_enabled(self) -> bool:
     def app_enabled(self) -> bool:
         return self.notifiers_status[NOTIFIERS.APP]
 
+    def valid_email_credentials(self, token: str) -> bool:
+        return self.notifiers[NOTIFIERS.EMAIL].check_credentials(
+            server="smtp.postmarkapp.com", port=587, token=token
+        )
+
     def send_notifications(
         self,
         node: AbstractNode,

packages/syft/src/syft/service/notifier/notifier_service.py

@@ -71,8 +71,15 @@ def turn_on(
         notifier.active = True
 
         # 4 - If email token is provided.
-        if email_token:
+        is_valid = notifier.valid_email_credentials(
+            token=email_token,
+        )
+        if email_token and is_valid:
             notifier.email_token = email_token
+        else:
+            return SyftError(
+                message="The token provided is not valid. Please provide a valid token."
+            )
 
         result = self.stash.update(credentials=context.credentials, settings=notifier)
         if result.is_err():
@@ -166,8 +173,13 @@ def init_notifier(
             if not notifier:
                 notifier = NotifierSettings(
                     active=active,
-                    email_token=email_token,
                 )
+
+                is_valid = notifier.valid_email_credentials(token=email_token)
+                if email_token and is_valid:
+                    notifier.email_token = email_token
+                else:
+                    notifier.active = False
                 notifier_stash.set(node.signing_key.verify_key, notifier)
         except Exception as e:
             print("Unable to create base notifier", e)

packages/syft/src/syft/service/notifier/smtp_client.py

@@ -58,3 +58,25 @@ def send(self, sender: str, receiver: List[str], subject: str, body: str) -> Non
 
             text = msg.as_string()
             server.sendmail(sender, ", ".join(receiver), text)
+
+    def check_credentials(self) -> bool:
+        """Check if the credentials are valid.
+
+        Returns:
+            bool: True if the credentials are valid, False otherwise.
+        """
+        try:
+            with smtplib.SMTP(self.smtp_server, self.smtp_port) as server:
+                server.ehlo()
+                if server.has_extn("STARTTLS"):
+                    server.starttls()
+                    server.ehlo()
+
+                if self.access_token:
+                    server.login(self.access_token, self.access_token)
+                elif self.username and self.password:
+                    server.login(self.username, self.password)
+
+                return True
+        except Exception:
+            return False