Am 21.09.26 um 09:51 schrieb Sebastian Hagedorn via mailop:
our help desk has notified me that mails from our SIEVE-based vacation
autoresponder aren’t accepted by Microsoft anymore. Microsoft complains about
the From address:
"The sender's domain in the 5322.From address doesn't meet the authentication
requirements defined for the sender"
I am guessing that refers to the envelope From, which is <> – as it should be
according to RFC 5230. The header From is using our domain, the outgoing messages are
DKIM-signed, and we have a DMARC policy. Regular messages are accepted by Microsoft,
so my best guess is that the empty envelope From is causing the problem. Is anybody
else seeing this? I don’t see how we can do anything about that on our end.
Your SPF "HELO" identity ist missing
kdig txt mail-out-v1.uni-koeln.de
RFC 7028 Sec. 2.4
"[RFC5321] allows the reverse-path to be null (see Section 4.5.5 in
RFC5321]). In this case, there is no explicit sender mailbox, and
such a message can be assumed to be a notification message from the
mail system itself. When the reverse-path is null, this document
defines the "MAIL FROM" identity to be the mailbox composed of the
local-part "postmaster" and the "HELO" identity (which might or might
not have been checked separately before)."
e.g.
kdig txt mail-out-v1.uni-koeln.de.
mail-out-v1.uni-koeln.de TXT "v=spf1 ip4:134.95.86.58
ip6:2a00:a200:0:13::58 -all"
-
Kind Regards
Jörg Backschues
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