On Thursday, May 6, 2021 at 6:46:06 PM UTC-7 Chris Peeples wrote:
Rick:
I’m on the list with a Yahoo account.
Chris and others,
From what I've been reading on other mailing lists, not all is sweet-smelling roses as far as migrating mailing-list(s) to Mailman using Yahoo.com addresses.
Directly quoting Rick from that post:
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DMARC is a badly designed antiforgery method designed by Yahoo that is
built atop an equally badly designed earlier antiforgery method named
DKIM. DKIM allows an individual user to cryptographically sign the
composed contents of his/her message, including many of the internal
SMTP headers. DMARC is a metastandard that includes DKIM, and adds
a method (SPF) to determine whether the IP address attempting to deliver
mail ostensibly from a claimed sending domain is among the IP addresses
predeclared as authorised to issue mail from that domain onto the
Internet.
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Why is this happening? Fundamentally, Yahoo designed an antiforgery
method (DKIM) that is hostile to mailing lists, not being willing to
take into account the need for software like Mailman to make some
changes to the body and headers of a subscriber's post, in making the
copies sent to fellow subscribers. All across the world, DKIM is
failing on mailing list postings sent through Mailman, Sympa, Majordomo,
Listproc, ezmlm, and all of the other mailing list managers.
_Any_ sending domain that declares a DMARC policy of "p=reject" or
"p=quarantine" causes massive problems for mailing list subscribers
receiving mail sent from a subscriber on that domain, _if_ the receiving
mail system implements the overly aggressive DKIM/DMARC policy request.
And, please note, this is not the user's fault, and the user cannot fix
the problem -- except by not participating in mailing lists from a
domain with a "p=reject" or "p=quarantine" DMARC policy.
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Please do read the remainder of that posting.
Michael's proposed Mailman upgrade to v3 might help (and both Rick and Michael are encouraged to elaborate upon this further) in reducing Yahoo.com's "DMARC badness".
-A