Test for open relay
How can I test if my firewall is being used for an email relay? I have landed on a couple of block lists, with the IP for the firewall being listed as the culprit. There is a mail server behind the firewall, and I have tested that and confirmed it is not relaying. That only leaves the firewall to be checked.
dotdash last edited by
Unless you installed postfix, it's not going to be the firewall. Probably some kind of spam mailer on a workstation. Add a rule to allow outbound smtp from your mail server, then block and log all other smtp traffic from the lan.
KOM last edited by