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:
javax.net.ssl.SSLException: Unsupported or unrecognized SSL message