I gotten a VPS recently and I wanted to host my own websites and with that, the ability to send and receive mail.
I set up my mail server according to this guide: https://www.exratione.com/2012/05/a-mailserver-on-ubuntu-1204-postfix-dovecot-mysql/
And it worked: I can access the SMTP with STARTTSL and IMAP server with authentication, all on standard port.
But now my Postfix turned into a spam server (currently it has 200+ mails queued up) and I was forced to turn it down. Also it always got all the MySQL connections, and websites couldn't connect to it.
How can I fix my Postfix?