SSL Errors on Email Notifier


I have a corporate mail SMTP relay server that I have input the host, port, and from email settings for. I've also specified 'SSL' for the 'Secure Connection' option. When using the 'Test connection' button, I get the below error.

Initially, I figured I needed to add the relay servers SSL cert as a trusted certificate. So I used openssl to retrieve the remote servers SSL cert, and saved it off in a .pem file. Then used the TeamCity Root project admin page for 'SSL/HTTPS Certificates' to upload this certificate. Then I went back to the Email Notifier settings and tested again, only to continue to see the below error.

TeamCity server is running as a Docker container, version is 2020.1.5 from the JetBrains TeamCity Server image in Docker Hub.

javax.mail.MessagingException: Could not connect to SMTP host: redacted-hostname, port: 25;
  nested exception is: Unsupported or unrecognized SSL message

I would double-check your port setting with your email provider. Port 25 is typically plain-text/unencrypted transmissions, but you're trying to use SSL. If it is plain-text coming through, it would certainly be considered an unrecognized SSL message.



Thanks Eric - great point. I confirmed with IT that the SSL option is not to be used with port 25. I set the 'SSL' option back to 'None', and the test email button gives me the 'Connection Successful' message - however I never receive the test mail.

IT confirmed that TeamCity is sending mail, but the mail server was refusing to forward it, so this issue is a mail server issue, not a TeamCity issue.


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