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Sendmail Tweaks

NOTE: AM Productions is not responsible for damages of any kind that result from the use/misuse of the following instructions.

Sendmail + Cyrus Pre-DATA To: Verify

2007-09-22

Starting yesterday we started 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 make 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 for the data is received we are now using the following: Address Verification FEATURE

Sendmail + Cyrus Local From: Verify

2005-06-22

Over the past week or so I've been receiving a lot of spam that forged the From: header of a non-existent user with my local domain. ie. somefakeuser@am-productions.biz. This became really annoying so I wrote some sendmail rules to lookup the "mail from:" and the "From:" header in the Cyrus (cyrusv2) database.

Instructions

  1. Cyrus v2.1.20 or greater. Lower versions may work, but 2.1.20 was what I'm using.
  2. Sendmail 8.13 or greater or Sendmail 8.12.7 with the socketmap patch.
  3. Beyond the normal Cyrus compile flags for Sendmail. You will need to compile it with -DSOCKETMAP.
  4. In /usr/local/etc/cyrus.conf add smmap cmd="smmapd" listen="/var/imap/socket/smmapd" prefork=0 to create the socket map.
  5. Restart Cyrus. killall -HUP master
  6. Add the from verify code to your .mc
  7. Rebuild your .cf and then stop and start Sendmail.cd /etc/mail && make && make install && make stop && make start
  8. Enjoy!

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