How well does DMARC mitigation work nowadays?
Specifically the kind where all list emails come from the the same address, with the sender in Reply-To?
It seems like this /should/ be the way it works. Isn't that what Reply-To is for?
Do some email clients still mess it up? If they do, wouldn't it make sense to just send them a bounce notice and tell them to clean up their act?
Context: considering moving to a paid email service like Mailgun or Twilio and having random unverified email addresses in the From: header seems to be a nonstarter for them, which makes sense.
If you have the sender address in the Reply-To:, do you still expect responses to go to the list?
-- Best regards, Odhiambo WASHINGTON, Nairobi,KE +254 7 3200 0004/+254 7 2274 3223 In an Internet failure case, the #1 suspect is a constant: DNS. "Oh, the cruft.", egrep -v '^$|^.*#' ¯\_(ツ)_/¯ :-) [How to ask smart questions: http://www.catb.org/~esr/faqs/smart-questions.html]
On Sun, Sep 28, 2025, 17:27 <tom@tomsmyth.ca> wrote:
Specifically the kind where all list emails come from the the same address, with the sender in Reply-To?
It seems like this /should/ be the way it works. Isn't that what Reply-To is for?
Do some email clients still mess it up? If they do, wouldn't it make sense to just send them a bounce notice and tell them to clean up their act?
Context: considering moving to a paid email service like Mailgun or Twilio and having random unverified email addresses in the From: header seems to be a nonstarter for them, which makes sense.
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On 9/28/25 07:27, tom@tomsmyth.ca wrote:
Specifically the kind where all list emails come from the the same address, with the sender in Reply-To?
It seems like this /should/ be the way it works. Isn't that what Reply-To is for?
Do some email clients still mess it up? If they do, wouldn't it make sense to just send them a bounce notice and tell them to clean up their act?
See https://gitlab.com/mailman/mailman/-/blob/master/src/mailman/handlers/dmarc.... for what we say about this.
I'm guessing that your concern is that a reply as opposed to reply all should go to the poster and not to the list. I think that will be
the case with most mainstream MUAs, but RFC 5322 is somewhat wishy-washy
about that saying only "When the "Reply-To:" field is present, it
indicates the address(es) to which the author of the message suggests
that replies be sent."
-- Mark Sapiro <mark@msapiro.net> The highway is for gamblers, San Francisco Bay Area, California better use your sense - B. Dylan
participants (3)
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Odhiambo Washington -
tom＠tomsmyth.ca