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Article: 112
From: Anthony Howe
Date: 2004-09-29 03:58:31 -0400
Subject: Re: from <> email message

Removal...........: milters-request@milter.info?subject=remove
More information..: http://www.milter.info/#Support

Nats wrote:
> I always keep has this entry on my log that dont have email address
> present(From <>) which is somewhat is guessing usernames on my email server
> (some kind of dictionary attacks), can milter-sender filter this kind of
> attacks?

No. You can't filter MAIL FROM:<>

1) You'd break bounce message reports.

2) You'd get listed on http://www.rfc-ignorant.org/ DSN Blacklist for 
not conforming to RFC 2821 et al.

3) milter-sender detects servers that don't accept MAIL FROM:<> and 
rejects them (sort of like RFCI's blacklist, but as a real-time test). 
So other milter-sender machines would reject mail from you if you block 

4) You'd break how milter-sender works. milter-sender uses the MAIL 
FROM:<> to perform the call-back. If you have two milter-sender MXes 
talking to each other and one or both fail to use MAIL FROM:<>, then you 
can end up with a mail-loop.

5) Other call-back filters would fail. I think I heard that Postfix has 
a call-back option too.

Anthony C Howe                                 +33 6 11 89 73 78
http://www.snert.com/       ICQ:
7116561         AIM: Sir Wumpus

            "Once...we were here."  - Last of The Mohicans

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