[166579] in North American Network Operators' Group
RE: Reverse DNS RFCs and Recommendations
daemon@ATHENA.MIT.EDU (Tony Hain)
Thu Oct 31 18:50:20 2013
From: "Tony Hain" <alh-ietf@tndh.net>
To: <nanog@nanog.org>
In-Reply-To: <20131031151302.60719.qmail@joyce.lan>
Date: Thu, 31 Oct 2013 15:49:56 -0700
X-SA-Exim-Mail-From: alh-ietf@tndh.net
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
John Levine wrote:
> Right. Spam filtering depends on heuristics. Mail from hosts without
> matching forward/reverse DNS is overwhelmingly bot spam, so checking =
for
> it is a very effective heuristic.
Leading digit is clearly in widespread use beyond 3com & 1and1. One of =
the most effective heuristics in my acl list is:
\N^.*@\d{3,}\.(cn|com|net|org|us|asia)
In the last few hours it has picked off multiple messages from each of =
these:
Carol28@8447.com
Jeff17@3550.com
Ronald79@0785.com
Kevin57@2691.com
Deborah76@3585.com
Kimberly34@5864.com
Sarah94@0858.com
zavfdv@131.com
qgmklyysyn@163.com
pjpeng@163.com
fahuyrw@163.com
Daniel57@4704.com
Helen95@2620.com
