[Mailman-Users] Messages discarded by ISP

Peter C.S. Adams peter.adams at umb.edu
Mon May 22 15:06:02 CEST 2006

Thus spake Mark Sapiro <msapiro at value.net>, circa 5/20/2006 9:26 PM:
> I just want to emphasize this. When you send via your mail client, the message
> is From: you and the envelope is most likely from you, but when you post to
> your list and Mailman sends, the message is still From: you (assuming you
> don't have an anonymous list), but the envelope is from
> <listname>-bounces at list.domain. Your ISP may well decide that a message
> purportedly from you at your.isp sent by some other domain is forged.

This is certainly possible, but I want to emphasize this: if the ISP is
doing this they are 100% WRONG!

RFC 2821 specifies that the envelope header "From" can -- and in some cases
MUST -- differ from the "From" in the message itself. There are a variety of
headers, such as From, Resent-From, Errors-To, and there are legitimate
reasons for all of them to be different.

If you find an ISP that is blocking mail from your list due to the makeup of
the envelope headers, you should encourage them to read the relevant mail
transport RFCs and invest in some decent Bayesian spam filtering software.
Then encourage your subscribers at that ISP to find another ISP

Peter C.S. Adams       (617) 287-7118
Director of Information and Communication Technologies
College of Public and Community Service, UMass Boston
"Be civil to all; sociable to many; familiar with few; friend to one;
enemy to none." -- Benjamin Franklin, Poor Richard's Almanack

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