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

[#1]

@plusnettony 

Does this report add something useful to the ongoing exploration?

[#2]

I have read this thread with interest because I have been trying to send (bcc) an email to several groups of people. Most of the Microsoft related destinations have bounced. Here is a specific example:

Group of 78 of which 17 are MS-related (13 hotmail, 1 outlook, 1 live, 2 msn)

1st attempt (via Outlook365): 12 of the 78 failed (9 hotmail, 1 outlook, 1 live, 1 msn)

2nd attempt (via Outlook365): 10 of the 12 failed (7 hotmail, 1 outlook, 1 live, 1 msn)

3rd attempt (via webmail): 0 of the 10 failed

I have since sent the email via webmail to some of the other groups of people (all of which contain MS-related addresses), with 0 failures.

Is that consistent with what has been reported hitherto and is it expected and explainable?

[#3]

I have the same success when using webmail. I'd like Plusnet to explain why e-mails to MS accounts are successful via webmail and those via their mail servers are unsuccessful.

[#4]

@abitpedantic 

Hello, a warm welcome to the forums.  There's nothing wrong with been a bit pedantic ... except when being very pedantic is what is required to cut through the FUD!!

This report certainly raises a lot of interest and somewhat pushes the issues firmly towards Microsoft where the big money has laid.  It would help if you could detail the failure codes from each NDR - I am guessing that they are all SPF=pass, DKIM=fail, DMARC=pass

@James_B / @plusnettony - does this anecdotal report help with the profiling and external discussions.  If this experience can be cohobated - no failures with Webmail (which is where I have been doing my testing and not reproduced the failures) but wide-spread failures with Outlook365 - is there enough evidence (even if only circumstantial) to push this back in to Microsoft's court?

[#5]

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@ebforum wrote:

I have the same success when using webmail. I'd like Plusnet to explain why e-mails to MS accounts are successful via webmail and those via their mail servers are unsuccessful.

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Sounds like you are asking Plusnet to explain why Microsoft's IMAP Email client fails, whereas Plusnet's webmail IMAP client (both connected to the same email servers) does not fail.

The party which needs to explain this variance is Microsoft, not Plusnet ... Plusnet's party piece seems to be working fine ... whereas Microsoft's appears not to.

[#6]

I don't care for that snippy comment.

We are in fact asking why sending via a Plusnet SMTP server does not work for email clients.

[#7]

@Townman, thanks for the explanation, it's a shame that this information has not been published as part of Plusnet keeping its customers briefed in relation a serious failure. In terms of IT service management, this problem is not attracting the level of comms from Plusnet that is commensurate with the severity of impact on its customers.

I'm left wondering if Plusnet's service management staff are accredited with ITSM/ITIL practices. Something I would have expected from a good organisation.

[#8]

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@PhilipHeyes wrote:

We are in fact asking why sending via a Plusnet SMTP server does not work for email clients.

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Is there evidence that this experience is being encountered with PC based email clients OTHER THAN Outlook365?

The request was to (effectively) explain why a third party's product fails, whilst Plusnet's webmail client does not.  I do not think that the suggestion that such is outside of reasonable expectations can be thought to be snippy.  I accept that might not be what folks want to hear: but such a question needs to be asked of Microsoft, not Plusnet.  The failure 'decision' making is somewhere in the innards of Microsoft's email services.

You will note that I asked staff if the observation might help in their exploration of the issues and pass the problem back to Microsoft.

If there are examples of this profile of failure being experience with other email clients as well, then that would be a different conversation.

The issue is indeed a pain, but asking PlusNet why a third party product fails, does not help ... indeed if it were known, one envisages, the problem would have been fixed by one or the other party weeks ago.

FWIW I asked for a public statement two days ago through the SU channel and chased it up again earlier today.

[#9]

Yes, they all have DKIM=Fail.

By the way, I have a native Plusnet email address i.e. you@youraccount.plus.com. A friend who has an IT company thinks that when the emails are sent from webmail, MS are not applying the bulk email tests that they apply when emails have come via Outlook365 because they don’t see the same structure in the Plusnet address. I’ve probably not expressed that very well but does it make any sense?

I don’t know whether he’s saying that when the source is webmail, you get DKIM=Pass or that you still get DKIM=Fail but it doesn’t matter – do you know? What my friend found particularly puzzling is why 5 of the 17 MS-related ones were apparently accepted and next time 2 of the 12. Does it mean that DKIM=Pass is generated occasionally or that occurrences of DKIM=Fail are sometimes allowed through?

[#10]

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@Townman wrote:

Is there evidence that this experience is being encountered with PC based email clients OTHER THAN Outlook365?

Yes, I refer to you my frequent posts about how I get failures using Outlook 2016 (from Office 2016 Pro Plus) via POP3.  OK so Outlook 2016 will be very similar to Outlook 365 but it won't be exactly the same.

[#11]

@abitpedantic 

Any out of the box thinking would be useful right now.

Would be good if your friend could explain their thoughts in detail.  The key difference between sending from a client and sending from webmail is the submitting client IP address.

Variable DKIM failure has a high probability to being linked to the know DNS timeouts within Microsoft world, but as @PhilipHeyes (and I think Peter) have pointed out, for the consistency of some user's experience, that seems statistically unsound.

Keep the ideas coming - I'm out of here now until tomorrow afternoon.

[#12]

@Townman, you are missing the crucial point. As a service provider, Plusnet should own the failures on behalf of its customers. If this means asking Microsoft to prove that it is handling e-mails from webmail differently to apps like Outlook365 then so be it. Breaking the problem down to "it's not my fault as I don't own Outlook365" is far from responsible.

Imagine an enterprise system manufacturer saying that "our system is OK and it must be Oracle's database software at fault". The enterprise manufacturer takes the whole responsibility on and determines in partnership with Oracle where the problems reside. They don't chuck the problem over the wall.

[#13]

@Townman said "Is there evidence that this experience is being encountered with PC based email clients OTHER THAN Outlook365?"

Yes, I get failures when sending using Thunderbird.

It's a bit random.  E.g. for one recent email to eight or nine fellow members of a committee, I got a bounce message from one with an Outlook.com address.  For a subsequent email to the same addressees, it was a Hotmail address which bounced, but not the Outlook one.

All recipients in the To field.  Dkim failure in both cases, SPF pass, DMARC pass.

What I can't say is whether there was a silent delivery failure when there was no bounce message, but it's clearly inconsistent.  It does however look like Microsoft applying stronger standards when the sender address is from username.domainname.com, with other random factors then potentially tipping the balance.

[#14]

The suggestion that the Windows MS Outlook email client is at the root of this needs to be dismissed as quite false.

We have a Win 11 HP laptop with MS Outlook current version installed.

MS Outlook is configured for multiple email accounts ( for different groups of customers )
with the email providers being 123Reg, gmail.com and Plusnet.

It is only sending via the Plusnet SMTP server that is constantly failing to deliver to any Hotmail / Live / Outlook addresses as part of a business messages to 5 to 7 recipients.

Sending via 123Reg and gmail.com is working with zero rejections from Microsoft accounts.

Claims that the current Plusnet configuration should work fine will not do,
it is like a garage saying "the car should be fine" but it can not be started.

[#15]

I don't think it is suggested that it is the 'Outlook' client that  it is causing the issue, rather that the MS receiving server is rejecting mail from PN addresses, due to the slightly 'different' address format.

@MisterW  - am I thinking correctly?