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I'm running two milters on my current postfix installation. I'm noticing that, from one particular client, they are sending an invalid command consisting of the first 3 letters of their domain name. When postfix sees this, it causes my milters to exit out.

How can I proceed past this?

I've seen this on the postfix documentation, but am not sure how to apply it:

milter_unknown_command_macros (default: see "postconf -d" output)
The macros that are sent to version 3 or higher Milter (mail filter) applications after an unknown SMTP command. See MILTER_README for a list of available macro names and their meanings.

This feature is available in Postfix 2.3 and later.


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up vote 2 down vote accepted

You could use smtpd_command_filter to exclude these bogus commands:

In /etc/postfix/

smtpd_command_filter = pcre:/etc/postfix/bogus_commands

And in /etc/postfix/bogus_commands:

/[^ ]{3}/ NOOP

You may have to test the regex to fit your needs.

There are no SMTP commands that consist of 3 letters :)

share|improve this answer
i like this. i'll give it a shot later today. – Larry G. Wapnitsky Apr 18 '12 at 10:25
i'm not a pcre guy, but this is replacing ALL commands that I enter with NOOP – Larry G. Wapnitsky Apr 18 '12 at 14:19
this seems to work: /^[^ ]{3}\s.*/ – Larry G. Wapnitsky Apr 18 '12 at 14:27
Yeah sorry about that - you have to match the non-character after the three initial characters to guarantee that it's ONLY three characters ;) – adaptr Apr 18 '12 at 15:02

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