MSFT jumped in on 05/05/2025 with their requirements. They also opted not to
slow-roll enforcement as Yahoogle! had but, instead, to just bounce mail from
the git-go.
Whilst they were using a specific bounce to indicate lack of compliance, it was
not this one. I've not noticed this one yet but will add it to our monitoring.
> 01000011 01110101 01110010 01101001 01101111 01110011 01101001
>
> 01110100 01111001 00100000 01101001 01110011 00100000 01110100
> 01101000 01100101 00100000 01101101 01101111 01110011 01110100
> 00100000 01110110 01100001 01101100 01110101 01100001 01100010
> 01101100 01100101 00100000 01100110 01100101 01100001 01110100
> 01110101 01110010 01100101 00100000 01101111 01100110 00100000
> 01101001 01101110 01110100 01100101 01101100 01101100 01101001
> 01100111 01100101 01101110 01110100 00100000 01101100 01101001
> 01100110 01100101 00101110
On Friday, November 6th, 2026 at 18:27, Thomas Johnson via mailop
<[email protected]> wrote:
>> On Nov 6, 2026, at 16:10, Jarland Donnell <[email protected]> wrote:
>>
>> Just today we've seen an error that I've never seen before from Microsoft:
>>
>>> 550 5.7.1 Message rejected: Message lacks SPF/DKIM/DMARC Auth Records
>>> (AS9031519)
>>
>> In each case, the sender domain has correct SPF and DKIM. From what we're
>> seeing, this just seems to trigger when the sender domain doesn't have a
>> DMARC record. So I guess DMARC is now a requirement to send mail to
>> Microsoft, they're pulling a Google and applying it at random, or they've
>> targeted us and our customers for it.
>>
>> Just looking for a bit of "Me too" or "We're not seeing that at all."
>> Perhaps even better, though wishful thinking, would be if anyone has any
>> certain knowledge on it.
>
> Us too!
>
> We're currently seeing this for just a portion of emails sent to hotmail.com
> or outlook.com. Happening for users with perfectly valid SPF and DKIM, but
> who are missing DMARC of any type.
>
> We did a quick note on our site about it:
> https://mailroute.net/docs/admin/outlook-message-lacks-spf-dkim-dmarc-auth-records
>
> We reached out to all our customers who were missing dmarc records and have
> encouraged them to at least add a basic p=none dmarc record to fix the issue.
>
> Tom
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