[Mimedefang] Net::DNS module for DNS lookups
Dave Shepherd
Dave.Shepherd at Vixel.com
Wed Jul 9 11:55:01 EDT 2003
I find in my spam logs a lot or email arriving from system that appear
to be home pc.
For example:
RelayHostname = 0x50a132cb.virnxx2.adsl-dhcp.tele.dk
ip = 80.161.50.203
To: user-deleted at vixel.com
From: tony_clarke_vt at FOR-2.COM
Subject: add 3 inches
If I perform a MX record lookup on the senders domain
# nslookup -q=mx for-2.com
Server: falcon.vixel.com
Address: X.X.X.X
Non-authoritative answer:
for-2.com preference = 50, mail exchanger =
mail-fwd.boca15-verio.com
These domains don't match ( 0x50a132cb.virnxx2.adsl-dhcp.tele.dk is
not FOR-2.com ).
This seem to be very typical of many spam messages. If a message is
From: friend at ibm.com
then shouldn't it be arriving from some system at hostname.ibm.com ??
What the effects would be if I rejected email in these cases. This could
easily
be done using the Perl module Net::DNS
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