After doing a update.sh on my Mailcow server, I’m having issues with sending email. When I try to connect using telnet to smtp server from other computers I get disconnect and these logs show up in the mailcow postfix log. However if I connect using telnet on the Mailcow host it works without issues. I’m at a loss at what could be the issue, as I have made zero configuration changes.
mail-postfix-mailcow-1 | Oct 18 18:07:31 ffec56be860d postfix/smtpd[401]: connect from unknown[10.xzy.xyz.xyz]
mail-postfix-mailcow-1 | Oct 18 18:07:34 ffec56be860d postfix/smtpd[401]: warning: non-SMTP command from unknown[10.xzy.xyz.xyz]: \377\373\037\377\373 \377\373\030\377\373′\377\375\001\377\373\003\377\375\003ehlo domain.tld
mail-postfix-mailcow-1 | Oct 18 18:07:34 ffec56be860d postfix/smtpd[401]: disconnect from unknown[10.xzy.xyz.xyz] unknown=0/1 commands=0/1