This generally occurs with a specific MTA. It is not a RFC compliant
behavior.
Pointing to an RFC rarely mitigates real-world concerns.
Indeed. We need deployment guides, but it's not clear to me whether
they'd better be IETF documents or written somewhere else.
I don't think they'd be very complicated or controversial, mostly a checklist
of remember to do this, and not to do that.
R's,
John
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