Jul 3 22:12:17mailserver postfix/smtpd: fatal: no SASL authentication mechanisms
Jul 3 22:12:18mailserver postfix/master: warning: process /usr/libexec/postfix/smtpd pid 6195 exit status 1
Jul 3 22:12:18mailserver postfix/master: warning: /usr/libexec/postfix/smtpd: bad command startup -- throttling
This only ever happens in my experience when the authentication method is actually Dovecot. Usually the problem........
The most common solution is to use the /etc/postfix/header_checks but this is a big problem.
Why is header_checks a problem? Because it does it to all mail whether incoming or outgoing and whether authenticated or not. We of course want as much header information for incoming as we can get for many reasons but many organizations want to secure and make their mail clients as secure as possible.
I adapted this solution to the client's custom config, they are configur........
This is a handy link and list of all the relevant Directadmin log files and related servers.
Basically you should always be 100% sure that whatever IPyour mail server sends out with has reverse DNS/PTR records. Remember that unless you own your IPs then you won't be able to set your own reverse DNS. Even if you were to create a reverse PTR record on your DNS servers it will be ignored. Reverse DNS is queried to pre-assigned DNS servers of your ISP, so therefore you'll need to contact your ISP/Colo/Hosting provider to do a reverse DNS entry.
If you don't have........