UnitedWare: Cincinnati, Columbus, Ohio IT and software consulting

Sendmail + Cyrus Pre-DATA To: Verify

By Anish Mistry

Background - 2007-09-22

Starting yesterday we began receiving lots of incorrect To: spam. This was causing the postmaster address to be slammed with lots of bogus messages. The problem is that by default Sendmail does not check with Cyrus until the entire message is received. So if mail is sent to an invalid address it will just get bounced to the postmaster address because of our local From: check. To hook Cyrus checking before the data is received we are now using the following: Address Verification FEATURE

Setup the From: check
Put ckuser_cyrus.m4 into /usr/share/sendmail/cf/feature/
Add FEATURE(`ckuser_cyrus')dnl to your .mc
Rebuild your .cf and then stop and start Sendmail.cd /etc/mail && make && make install && make stop && make start

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