On 2023-12-19 at 07:42:56 UTC-0500 (Tue, 19 Dec 2023 13:42:56 +0100)
MM_Arc via mailmate <[email protected]>
is rumored to have said:
Hello,
I notice that some posts on the list have the format “XXX via
mailmate” and others don’t.
I’m trying to figure out the reason why
It's because the mailing list software (Mailman 2.x, assuming the
headers are not being intentionally misleading) is configured to avoid
having people's posts rejected due to a mail authentication mechanism
called DMARC. Many-to-many mailing lists such as this one intrinsically
violate the assumptions of DMARC, which is a tool really designed for
the needs of big bulk mailers and big mailbox providers.
Mailman modifies the "From" header of messages sent from domains which
would otherwise be widely rejected (or delivered to a "spam" folder) as
if they were forged, if they kept the original From header. The DMARC
protection configuration in Mailman is a complex set of settings that
varies between lists, and it's a bit of a kludge conceptually, so I
won't try to pick apart the precise details for this list. Perhaps Benny
can explain the specific rules.
and how this can be changed.
To make your messages not have their From "munged" by Mailman, you'd
need to figure out how to 'game' Mailman to leave them alone. That's
dependent on your domain's DMARC record in DNS and possibly on the
configuration of your outbound mail system, e.g. whether and how it
signs messages using the DKIM mechanism that DMARC utilizes and possibly
whether you domain has a restricting SPF record.
You cannot change how other people's From headers appear on the messages
you get from the mailing list. It may be possible to create a custom
layout for MM to find the hidden 'real' sender address and display that,
but I'm not sure if Benny has provided enough logic in the layout system
to support that.
There is probably no solution that you would find satisfying, without
Benny adding a lot of complex logic to work around the quirks of how
Mailman can munge headers. I hope he does not make that attempt, as it
is likely to have a remarkably large number of edge and corner cases.
--
Bill Cole
[email protected] or [email protected]
(AKA @grumpybozo and many *@billmail.scconsult.com addresses)
Not Currently Available For Hire
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