Improvements
2- The SASL library and the PLAIN, LOGIN, CRAM-MD5, DIGEST-MD5, SCRAM and ANONYMOUS mechanisms are now part of the package itself, so the behaviour is identical on AlmaLinux, Rocky, Debian and Ubuntu and no operating-system package has to be installed. Everything else the package needs is unchanged from the previous release.
- Your Postfix configuration is not touched by this update: main.cf and master.cf stay exactly as they are, and incoming mail authentication keeps using Dovecot as before.
Bug Fix
1- Outgoing mail through a relay host that requires a username and password now works. Postfix was built without its SASL client, so every authenticated relay (SMTP2GO, SendGrid, Mailgun, Amazon SES, Gmail and others) failed on the first real message with "unsupported SASL client implementation: cyrus", even though the panel's connection test passed. The test used its own connection, which is why the problem only appeared when mail was actually sent.