From: Steve Freegard
Date: 2008-12-03 11:31:40 -0500
Subject: Re: milter-null and DSN/MDN messages
More information..: http://www.milter.info/#Support
Greg Matthews wrote:
> Hi Steve...
> Steve Freegard wrote:
>> Either pass -one-rcpt-per-null in the start-up options or edit your
>> milter-null.cf file (defaults to /etc/mail/milter-null.cf) and change
>> the same option as it currently defaults to +one-rcpt-per-null (+ = on,
>> - = off) see http://www.snertsoft.com/sendmail/milter-null
> I was wary of doing this as I didn't necessarily want to turn this
> functionality off for all domains but a quick look at the logs over the
> last week shows that this doesn't seem particularly effective as an
> anti-spam technique. I think it is almost entirely hitting these
> automated forwards.
It's an RFC conformance option - the RFC states that messages from the
null-sender should only be to a single recipient and it's only really
cases like yours that might be a problem, so it's really for
defence-in-depth - the spammers don't do this now, but they might start
sometime in the future:
[root@mail ~]# echo STAT | nc localhost 25 | grep -P '(
214-2.0.0 age=1212139 (14 00:42:19)
214-2.0.0 015 CLIENTS=5197232 (100.00%)
214-2.0.0 099 one-rcpt-per-null=0 (0.00%)
> Thanks for the response - didnt realise you lurked here too!
No problem - Anthony and I are good friends since our work on
BarricadeMX together, so I have knowledge of the milters as well as some
of it is common code (such as one-rcpt-per-null) and they also share the
same configuration syntax. So I lurk here and post whenever anything
appears that I can help with.
Copyright 2009, 2012 by SnertSoft. All rights reserved.