Tag Archives: spam

Configure Postfix for DNS Blackhole Lists

Posted on by
Reply

Followed the instructions in this article Configure Postfix for DNS Blackhole Lists such as dsbl.org / spamhaus.org database to configure my Postfix email server to stop spam. I used the whole recommendation:


smtpd_recipient_restrictions =
   reject_invalid_hostname,
   reject_non_fqdn_hostname,
   reject_non_fqdn_sender,
   reject_non_fqdn_recipient,
   reject_unknown_sender_domain,
   reject_unknown_recipient_domain,
   reject_unauth_destination,
   permit_mynetworks,
   reject_rbl_client list.dsbl.org,
   reject_rbl_client sbl-xbl.spamhaus.org,
   reject_rbl_client cbl.abuseat.org,
   reject_rbl_client dul.dnsbl.sorbs.net,
   permit

Before that my settings where:


smtpd_recipient_restrictions =
  permit_mynetworks,
  permit_sasl_authenticated,
  reject_unauth_destination

I kept the permit_sasl_authenticated setting too.

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.

Today’s spam

Posted on by
36

I noticed this in my inbox today, it got past the spam filter:

“If all you dream about is pain relief, why are you still living? It is not real life!”

It’s fun to interpret it in different ways. And it’s kind of shocking as an advertisement.

The reality of AI

Posted on by
59

I think this is rather amusing.

If you go to the AI-class FAQ the first thing you will see is:

Q: What if I don’t receive a verification e-mail after submitting my enrolment?

A: Confirm that it is not in your spam box.

Which is funny, isn’t it? I mean, it’s applied AI that is doing your spam filtering, and the most likely cause of you not getting your email from the AI-class is that the AI that’s filtering your mail is wrong with a false-positive.

Well I think it’s funny. :P