On Tue, 8 Mar 2005, Miles Libbey wrote:
I was talking to an MTA developer at MAAWG last week, and he thinks that there
are 'a lot' of legit domains that HELO with non-domain text (garbage text).
Regardless of the RFC compliance of this action (and what 'a lot'
constitutes), I thought it might be interesting to find some data on this
behavior.
I did some analysis of this in December. According to my numbers "a lot"
is about 1/3 of legitimate email senders, and a rather higher proportion
of spam and viruses.
http://www.livejournal.com/users/fanf/30030.html
http://www.livejournal.com/users/fanf/30241.html
This doesn't include syntactically invalid HELO domains - Exim rejects
those - and it doesn't include domain literals, which are also frequently
bogus.
Tony.
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