Tag Archives: header_checks

Postfix header checks

Posted on by
Reply

I wanted to do something about the fact that I get a lot of spam where the date is substantially in the past, that is, months or years ago.

I figure I’ll never get any mail that I care about where the date is set that far back so what I wanted was a way to filter out such email.

There didn’t seem to be any suitable option in Thunderbird, and I’d rather have this done on the server than the client anyway, so I started fishing around for options in Postfix.

I found out about header checks.

To enable I had to add a file to the header_checks configuration option in /etc/postfix/main.cf:

header_checks =
  regexp:/etc/postfix/header_filter_map
  regexp:/etc/postfix/spamheadercheck

Then I created a header_filter_map file with some regexes for the date:

/^Date: .* [JFMASOND][aepuco][nbrynlgptvc] 1\d\d\d/ DISCARD Date 1
/^Date: .* [JFMASOND][aepuco][nbrynlgptvc] 200\d/ DISCARD Date 2
/^Date: .* [JFMASOND][aepuco][nbrynlgptvc] 201[0-1]/ DISCARD Date 3
/^Date: .* Jan 2012/ DISCARD Date Jan
/^Date: .* Feb 2011/ DISCARD Date Feb
/^Date: .* Mar 2011/ DISCARD Date Mar
/^Date: .* Apr 2011/ DISCARD Date Apr
/^Date: .* May 2011/ DISCARD Date May
/^Date: .* Jun 2011/ DISCARD Date Jun
/^Date: .* Jul 2011/ DISCARD Date Jul
/^Date: .* Aug 2011/ DISCARD Date Aug
/^Date: .* Sep 2011/ DISCARD Date Sep
/^Date: .* Oct 2011/ DISCARD Date Oct
/^Date: .* Nov 2011/ DISCARD Date Nov
/^Date: .* Dec 2011/ DISCARD Date Dec

I also found this file so I added some rules for the X-Mailer header, like this:

/^X-Mailer: 0001/                               DISCARD Mailer 1
/^X-Mailer: Avalanche/                          DISCARD Mailer 2
/^X-Mailer: Crescent Internet Tool/             DISCARD Mailer 3
/^X-Mailer: DiffondiCool/                       DISCARD Mailer 4
/^X-Mailer: E-Mail Delivery Agent/              DISCARD Mailer 5
/^X-Mailer: Emailer Platinum/                   DISCARD Mailer 6
/^X-Mailer: Entity/                             DISCARD Mailer 7
/^X-Mailer: Extractor/                          DISCARD Mailer 8
/^X-Mailer: Floodgate/                          DISCARD Mailer 9
/^X-Mailer: GOTO Software Sarbacane/            DISCARD Mailer 10
/^X-Mailer: MailWorkz/                          DISCARD Mailer 11
/^X-Mailer: MassE-Mail/                         DISCARD Mailer 12
/^X-Mailer: MaxBulk.Mailer/                     DISCARD Mailer 13
/^X-Mailer: News Breaker Pro/                   DISCARD Mailer 14
/^X-Mailer: SmartMailer/                        DISCARD Mailer 15
/^X-Mailer: StormPort/                          DISCARD Mailer 16
/^X-Mailer: SuperMail-2/                        DISCARD Mailer 17

Now that I know how to do this I’ll start adding rules for particular spam that I seem to get a lot of.

I’m not sure if I made the best decision, but I decided to silently discard email rather than reject it.

Ignoring emails with old dates

Posted on by
38

I was reading about Postfix’s cleanup facility which supports header_checks which can be specified in a regexp: table. And it inspired me to come up with this header_filter_map file:

/^Date: .* [JFMASOND][aepuco][nbrynlgptvc] 1/ REJECT
/^Date: .* [JFMASOND][aepuco][nbrynlgptvc] 200/ REJECT
/^Date: .* [JFMASOND][aepuco][nbrynlgptvc] 2010/ REJECT
/^Date: .* [JFMASOND][aepuco][nbrynlgptvc] 2011/ REJECT
/^Date: .* Jan 2012/ REJECT
/^Date: .* Feb 2011/ REJECT
/^Date: .* Mar 2011/ REJECT
/^Date: .* Apr 2011/ REJECT
/^Date: .* May 2011/ REJECT
/^Date: .* Jun 2011/ REJECT
/^Date: .* Jul 2011/ REJECT
/^Date: .* Aug 2011/ REJECT
/^Date: .* Sep 2011/ REJECT
/^Date: .* Oct 2011/ REJECT
/^Date: .* Nov 2011/ REJECT
/^Date: .* Dec 2011/ REJECT

Which I applied in Postfix by adding the following line to /etc/postfix/main.cf:

header_checks = regexp:/etc/postfix/header_filter_map

It remains to be seen if what I’ve done will work, and at the moment this is a bit of a pain because I have to manually update the header_filter_map file every month, but the general idea is that if the regexp matches a date too far in the past then the message is rejected. Hopefully then those spammers who have messages turning up in my history will be gone.