This is from the NANOG list. Is anybody else attempting to prevent
backscatter by blocking emails from customers using smtp auth that the
sender is <> or postmaster (and recipient is not local)? This is not
something I have ever considered, looking to see if anybody else has.
Regards... Todd
---------- Forwarded message ----------
From: Eric J Esslinger <eesslinger at fpu-tn.com>
Date: Wed, May 25, 2011 at 9:09 AM
Subject: blocking annoying 'bounce mail' "feature" from customers use.
To: "nanog@???" <nanog at nanog.org>
Mac Mail (and others) have a "feature" that allows my customers to
generate a fake NDR message and send it back through my server. I get
about a customer every few months that discovers this 'solution' to
spam emails, and when it happens they cause delivery problems for my
customer mail server by generating backscatter.
Today I just ended up on a list that won't take me off for quite a
while (or unless I pay).
Does anyone know of a way for me to block the following, using
postfix, either via refusing to accept the mail or by dropping it in
/dev/null:
Mail from <> or postmaster that originates within our customer IP
blocks/is sent using authentication at the submission port and/or that
does not have a valid local recipient.
I can't find any ready made recipies online for this sort of thing in
a short dig around for it, and while I think it's possible, I was
wondering if anyone else was already dealing with this and could say
'oh yeah just put line blah in header_checks'. I would think it would
be simple once you find it but you know how it is.
(I've already dealt with the customer in question but I'm getting
tired of this popping up every month or three.)
__________________________
Eric Esslinger
Information Services Manager - Fayetteville Public Utilities
http://www.fpu-tn.com/
(931)433-1522 ext 165
This message may contain confidential and/or proprietary information
and is intended for the person/entity to whom it was originally
addressed. Any use by others is strictly prohibited.
--
Regards... Todd
"It is the nature of the human species to reject what is true but
unpleasant and to embrace what is obviously false but comforting."
"You might be a skeptic if you have pedantically argued the topic of pedantry."
