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Sat, 04 Oct 2008

/Admin/email/postfix: Blocking SPAM

For the simple case of blocking/bouncing a particular e-mail address, create a file /etc/postfix/spammer containing something like the following:

spammer@domain.com REJECT
spammer2@spamcentral.net 554 Die Spammer, die!

Note that a full list of possible return codes can be seen in RFC-821[1].

Then run

postmap spammer

to generate a db file for postfix. Add the following line to /etc/postfix/main.cf:

smtpd_sender_restrictions = reject_non_fqdn_sender, check_sender_access hash:/etc/postfix/spammer, permit

Note that "reject_non_fqdn_sender" will bounce any e-mail coming from an address that does not have a fully-qualified domain name.

Restart postfix:

/etc/init.d/postfix restart

That simple.

Some useful resources: http://www.securityfocus.com/infocus/1593
http://www.postfix.org/SMTPD_ACCESS_README.html
http://www.yolinux.com/TUTORIALS/LinuxTutorialMailMTA.html
http://www.akadia.com/services/postfix_uce.html

[1] http://www.ietf.org/rfc/rfc0821.txt

posted at: 03:04 | path: /Admin/email/postfix | permanent link to this entry

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Sat, 04 Oct 2008