From address doesn't meet the authentication requirements defined for the sender

[#1]

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@Townman wrote:

Its work in progress...

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I can also report that a test message to an @live address didn't bounce / was delivered and it landed in the recipient's Inbox, not the Junk folder.

Superficially that's my problem fixed but I can't hear the fat lady singing so I doubt it's all over yet.

[#2]

Well, the fat lady did sing to me but she was a bit out of tune.

I think you're right, we haven't heard the last of this.

[#3]

It's now been fixed, for me at least!  I can send to hotmail addresses again.  Thanks to all involved.

[#4]

I just sent a message to an ntlworld address (ntlworld no longer exists but I see it can be set up as an alias on outlook) and outlook bounced it (" **.plus.com....doesn't meet the authentication requirements defined for the sender"). So not there yet?

[#5]

Oops, I spoke too soon - despite the rejection message from Outlook, the recipient (on Ntlworld/Virginmedia) has now received it! (Except that the background to the text had been turned black so it had to be highlighted to read it.) Weird.

[#6]

I'm guessing MS are intentionally playing silly sausages - but I could be wrong, of course.

[#7]

If I forward an email to one hotmail account individually it seems to go through. If I include multiple addresses, it is still bouncing

[#8]

Ooh yes, I find the same thing. I wonder how Outlook knows that the message has been sent to others, on other servers. Perhaps it looks at the list of recipients to see if they are known risks. Could try the same trick with other recipients blind copied....

[#9]

I too can report that if I send a message to both an @live and an @outlook address, both messages bounce immediately.  In both cases, the details say:

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Spf= Pass , Dkim= Fail , DMARC= Pass

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Meanwhile, sending to just one recipient (@live) still works.

[#10]

Spf= Pass , Dkim= Fail , DMARC= Pass

I'm not sure how that can be ? do the headers give any more clue why it thinks DKIM is fail ?

[#11]

@stuck  @MisterW 

What does the DKIM header say on the one to a single Live address?

If it has also failed, then maybe Microsoft's spam filter is using DKIM as one of many factors in its scoring system, perhaps with a fairly high weighting.  If so, then by itself a DKIM fail might not trigger a bounce?  But in combination with other factors it might.  And having multiple recipients might tip the balance?

This may be completely wrong!  But either way, I don't think Plusnet emails should be failing DKIM.  AIUI, it suggests a mismatch when Microsoft compare the hashes of PN's public and private keys.

[#12]

@Tim-J now that reminded me of this https://www.uriports.com/blog/outlook-com-dkim-temperror-in-dmarc-reports/

I have a number of domains hosted elsewhere, all of which are correctly configured with SPF,DKIM and DMARC. 

I do notice in DMARC reports from outlook.com that often there is

<dkim>
<domain>xxxx.org.uk</domain>
<selector>mythic-beasts-k1</selector>
<result>temperror</result>
</dkim>

So it would seem MS is still having issues with DKIM processing.

In my case it doesnt matter because in no way can any of my domains be classed as a 'bulk sender' and so my email is still accepted purely on SPF pass. 

Since MS are classing plus.com as a bulk sender and thus now requiring SPF & DKIM, it would seem that the first thing they ought to have done was to ensure that they were handling DKIM DNS lookups correctly!!

[#13]

@MisterW 

Yet earlier in the thread (e.g. message #21) PN emails to MS were passing DKIM while failing SPF.  Now it's the other way round.

[#14]

@Tim-J they're now passing SPF because work has been done to add SPF records to all <account>.plus.com domains.

DKIM was always configured and still is.

[#15]

So, and excuse me for being blunt, M$ have decided to throw another 'non-standard' spanner in the works - or so it seems?