Is there any way to filter outgoing mail for spam? Does outgoing mail pass through Spamassassin, or does that only apply for inbound mail? We’ve had a a couple of incidents where something gets onto a user’s machine, and starts spamming using the legitimate credentials, which then causes the server to be blacklisted.
The only other way I can think of is to route all outbound mail through another mail gateway running something like MailScanner. What would be the easiest way to accomplish outbound mail routing via another mail server?
If an improvement to the MIAB code allowed adding a smarthost(relayhost) (possibly to the /etc/postfix/main.cf), this problem of yours…and mine…would be solved. I’m hoping my request in ‘improvements’ gets serious consideration. Nowadays, scanning all your outgoing on a reputable spam filter service is a necessity. Basic built in spam filters don’t quite cut it anymore.
You can can check on diffirent services like http://www.mail-tester.com or http://www.isnotspam.com/ if your mail has a good reputation.
However, even having 10 won’t prevent your mail from being flagged spam by the recipients email servers, for reasons I am searching for.
This probably will get you in trouble when DNSSEC is enabled.