I'm getting mailbombed
Problem: I am receiving hundreds of emails per day from spammers. They appear to be coming from 2 sources (forged addresses). We have always received some spam, but recently it has tripled. As the administrator, I am receiving email notifications from the postmaster that the email was undelivered (a good thing), but how do I stop them from hitting my box at all?
Background: We are using the combination of Red Hat 9.0 and Sendmail for our email server. We are also using Spamassassin as well as Trendmicro Internet Firewall to block dirty mail. We allow incoming mail to hit our email server, but outgoing mail does not. So, I feel confident we are not being used as a relay, but they are sure trying.
I have tried to blacklist domain names, IP's and specific email address' through spamassassin.
I have also gone into the sendmail access file and added the domain names, IP's and specific email address' to DISCARD.
Is there anything else I can do?
Thanks from newbie,