On 12 Apr 2023 04:12, The Wanderer 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.
Thanks for the details ! This is exactly what's happening.