On Wed, 1 Mar 2006, Dick St.Peters wrote:
If I recall correctly, you said in an earlier post that Verizon won't
accept SRS mail, yet I run SRS and regularly send mail to @verizon.net
addresses. So I can say with certainty that Verizon does not refuse
or bounce SRS mail as a matter of routine.
I didn't say SRS mail. I said that certain MFROMs were rejected, while
others were accepted - for the same domain, from the same IP. This
is true on a manual SMTP session as well. I asked if anyone knew their
algorithm. The server in question is relay.verizon.net.
Based on your experience, I tested from various mail servers. Apparently,
they accept SRS MFROMs from most IPs, but not all.
The client in question hired me because his server was being used as
a high volume bounce spam relay (where the spammer sends deliberately
misaddressed mail from Windoze zombies all over the world with an MFROM for the
intended target). So verizon may have his IP on some kind of blacklist. But
why they think rejecting SRS MFROMs helps is beyond me. The bounce spams
had an <> MFROM.
I initially installed pymilter to block forged MFROMs. This was effective
in stopping the attack, but it could only handle about 120000 connections
a day on his 400 Mhz PII, whereas his system was relaying 2.5 million
bounce spams a day. As a result, legitimate mail was getting delayed
by 6 to 8 hours. Instead of upgrading his server, we signed
up with spamsoap.com - which handles billions of such trash connections
a day.
--
Stuart D. Gathman <stuart(_at_)bmsi(_dot_)com>
Business Management Systems Inc. Phone: 703 591-0911 Fax: 703 591-6154
"Confutatis maledictis, flammis acribus addictis" - background song for
a Microsoft sponsored "Where do you want to go from here?" commercial.
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