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Old 02-13-2004, 12:38 PM   #1
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Sendmail - Check for Bad From Address?

Can Sendmail be configured to drop or reject the following type of problem mail? My version is 8.11.6 running on RH 7.3

(log example)

from=<>, size=0, class=0, nrcpts=0, proto=SMTP, daemon=MTA, [] (may be forged)

I am getting a couple hundred of these attempts logged every day now for about two weeks. They originate from various domains, but all are sent to generic user names AT my domain.


Of course, none get delivered because I have no such users and my only real damage (I think) is that my logs are getting filled up with these junk entries. But I would like to stop this traffic if at all possible.

When I looked into this subject at, it seems that Sendmail has some type capability for checking M4 files I believe.

Is it possible to reject messages with the "from=<>" part of the message being empty?

Thanks for any advice or help.

Old 02-13-2004, 01:08 PM   #2
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from=<> is a legitimate from address. It's used by automated systems to send bounce messages, etc. This is a defense against accidental mail loops, so I strongly recommend you don't drop messages in this format.
Old 02-15-2004, 12:00 AM   #3
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Your generic addresses sounds very much like the M.O. of the MyDoom virus. It will send out mail to people in address books and also to Jane@ George@ Cindy@ etc.... It will slow down after a while. It has for the organization I am at.
Old 02-15-2004, 11:55 AM   #4
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Thanks for the info...seems I have nothing to worry about then either way. ;-)


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