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

[#1]

@Townman 

Re #758

So, just to be clear, are you saying that Plusnet’s avasout servers appearing on block lists is nothing to do with the DKIM failures i.e. the huge number of emails rejected due to DKIM failures has not contributed to the reputation of the sending servers?

Therefore, is it realistic to expect that Plusnet should be able to get the servers de-listed soon and then we will be back to the original problem, which it seems to be possible to get around by sending plain text emails?

Note that I am assuming that the DKIM failure issue will not be resolved as Plusnet continue to refuse to comment on it.

[#2]

I found this to be interesting : https://www.mailgun.com/blog/deliverability/outlook-dkim-rejection/

[#3]

@PhilipHeyes Me too. It appears M$ are determined to break any mail provider, unless they are one of theirs, for some not particular reason.

Thanks for the info.

[#4]

@PhilipHeyes
Excellent sleuthing! I appreciate it may not be the whole answer, but please will the Superusers feed into the business.

[#5]

but please will the Superusers feed into the business. 

Done.

[#6]

I see that the Mailgun article is date June 30th and that near the end it says:

"it’s a broader issue stemming from Microsofts evolving filtering behaviors. We’re in the thick of it with the rest of the industry, and we’ll continue to share what we learn."

I didn't find a follow-up article.

[#7]

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@PhilipHeyes wrote:

I found this to be interesting : https://www.mailgun.com/blog/deliverability/outlook-dkim-rejection/

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Excellent article on many fronts, which supports much of what has been said around here for weeks (or is it now months) but dismissed roundly by many of the thread's pundits...

• This is not an issue only impacting Plusnet as many have sought to assert
• Even where everything is demonstrably correct, it can fail (only apparently in Microsoft's universe)
• Microsoft are clearly up to no good for reasons no one knows and they are not saying

There are some interesting ideas herein which could be explored, but logically do not make a hap'eth sense: a DKIM pass in one environment should pass in all environments and not be predicated by the character set, the email client or the number of addressees.

[#8]

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@abitpedantic wrote:

@Townman 

Re #758

So, just to be clear, are you saying that Plusnet’s avasout servers appearing on block lists is nothing to do with the DKIM failures i.e. the huge number of emails rejected due to DKIM failures has not contributed to the reputation of the sending servers?

Therefore, is it realistic to expect that Plusnet should be able to get the servers de-listed soon and then we will be back to the original problem, which it seems to be possible to get around by sending plain text emails?

---

The cited excellent article seems to have overtaken this post...

• I do not believe that the black listing is in any way related to Microsoft's questionable DKIM failures
• Del-listing will probably be predicated on closing down the bad actors who have injected so much spam into the network - there are hints that individual users are being contacted requiring them to conduct virus and malware scans

[#9]

@Townman said: "This is not an issue only impacting Plusnet"

However, note that the article suggests that subdomain addressing (like Plusnet's) is more vulnerable.

@Townman : "Microsoft are clearly up to no good"

Hanlon's razor may apply: "Never attribute to malice that which is adequately explained by stupidity."

[#10]

I think it suggests that COMPLEX sub-domaining (as in @a.b.c.d) is thought could be a factor and that was only in the space of DMARC alignment.

Many organisations use email domain structures the same as Plusnet's; it is not something which can be changed, so there's little point considering it.  Microsoft is wrong - end of - I do not understand why so many seem inclined to ignore that truth or defend them.  Plusnet, like Mailgun are very much shooting in the dark here and there is no visibility that Microsoft are willing to engage.

If this were an error or incompetence, I am sure that Microsoft would have fixed it by now.  They have not, so its not explained away by stupidity, therefore the presumption of malice seems fair.

[#11]

Agreed, @Townman .

[#12]

I'm not defending Microsoft. I'm accusing them of stupidity. Please don't assume that your criticism of them is the only valid one.

On subdomain addressing structures, my reading of the article was that the deeper the subdomain structure, the more likely it was to be hit by Microsoft's misconfiguration.

[#13]

Hi Tim,

Depth - yes the article did refer to that, but that was at a 2nd level of sub-domains, not the first and was in the context of DMARC alignment.

Mailgun's article thereby hints at the strict / relaxed alignment not being honoured ... and with complex domain name structures, establishing strict alignment brings about complications.

Strict alignment would required a distinct DMARC record for every user.

[#14]

Dont forget that DKIM failures from Microsoft are not limited to the use of sub domains, its just that the results of a failure are more apparent when sub domains are used and the sender is being treated as a 'bulk sender' by Microsoft i.e the mail is rejected.

I have domains hosted elsewhere. I regularly see DKIM failures from Microsoft in my DMARC reports, but in my case I'm not classed as a 'bulk sender' so my mail still gets delivered.

[#15]

Dear All

I raised a ticket on this issue having discovered a little information about this problem but before discovering this thread.  I received a call from an agent and discussed the circumstances causing me a problem (one hotmail user, long non delivery email delay and depending on client used to send possibly no non-delivery email). I mentioned this thread which now runs to 52 pages.  He escalated the issue.  It took 3 days for him to get a response (again I got a phone call) the gist of which is 

Sadly, I have been informed that our back office team is aware of the issue, but I have not got any timescales for a repair."

In the call there was also the suggestion of creating a new mailbox to send from.  I have an open ticket on this issue but whether that will yield an update I think unlikely.  I impressed upon him that I thought Plusnet ought to make a statement about this issue.

Phil