I'm getting lots of junk "return to delivery" mail on my server, so I would like to add this "RDNS" lookup thing in Ubuntu.
But I can't figure out how. Most documentation is about regular DNS servers.
I'm getting lots of junk "return to delivery" mail on my server, so I would like to add this "RDNS" lookup thing in Ubuntu.
But I can't figure out how. Most documentation is about regular DNS servers.
Assuming from the tagging of the question that your mail server software is Postfix, you can tune this via the smtpd_client_restrictions variable as described in postconf(5)