On Tue, Apr 11, 2023 at 10:12 PM The Wanderer <wande...@fastmail.fm> wrote: > > ... > Some mail services apparently treat this "discard incoming messages that > look like duplicates of ones you already have a copy of" behavior as a > feature; Gmail is the best-known example. That has problems when (as > with this mailing list) the incoming copy is not identical to the one > that was sent, even though it has the same Message-ID, but AFAIK they > don't seem to care.
I believe Message-Id's are supposed to be unique across space and time. It sounds like discarding the duplicate is expected behavior (to me). I don't think I would blame GMail for that. Maybe it's the sender's MUA? Also see https://en.wikipedia.org/wiki/Message-ID . Jeff
