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

[#1]

Towbman wrote

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.

I totally agree but as we are all customers of PlusNet and they get our money, we expect PN yo provide a working serviceis PN is our first and only port of call and whoever is to blame, this needs to be resolved quickly.

I have read with interest all 240 messages that are sitting in a folder in my email client and I am getting a little fed up with the whole issue.

I have many accounts and none of them have sub-domains like PN. btinternet.com, me.com, gmail.xom, googlemail.com, mac.com etc. and none of them have my user name after the @ symbol. None of these accounts when contacting MS addresses either individually or in bulk, bounce. While I am a very experienced mainframe engineer I do not profess to be an expert with email but there is obviously some correlation here.

Now it's time to have a very large whisky and get ready for a quiet life.

PS. I am not a PN customer (I use Sky) but I am helping an elderly lady (G Solodchin) who luckily, no longer has a problem as she only emails 1 person at a time. We both use Apple Mail as email clients but also tried Thunderbird when we she had the initial problem. Web Mail also failed but I think you all know this.

Anyway, good luck to you all .............

[#2]

@solodchin You have kind of hit the nail on the head there - all the other mail providers don't give their users a sub-domain. which allows them to have various 'addresses', should they wish to make use of the facility. Unfortunately, MS appear to be ignoring the sub-domains and treating everyone as if their address was 'xxxx@plus.com', therefore invoking their bulk sender policy.

[#3]

"Unfortunately, MS appear to be ignoring the sub-domains and treating everyone as if their address was 'xxxx@plus.com', therefore invoking their bulk sender policy."

But not if you send via webmail, it would seem (e.g. see #384). At the moment, I don't think we have an explanation from anyone as to why this works.

[#4]

It works because it works as per the instructions.

The question to explore is why do other clients not work under the same back end server configurations?

I fear that I'm going to have to set-up an Outlook client on some test accounts ... which I did not really want to do.

[#5]

Good luck.

[#6]

But not if you send via webmail, it would seem (e.g. see #384). At the moment, I don't think we have an explanation from anyone as to why this works.

I'm also intrigued as to why sending using webmail should be any different ?

After all, webmail is just another email client, all clients use the same protocol (SMTP) to send mail. Webmail just happens to be a mail client which runs on a remote webserver and allows email functionality via a web browser.

In essence sending mail is a two-stage process, the mail client connects to their mail server to 'submit' the email, if accepted, the mail is stored. The mail server then looks up the receiving mail server and attempts to transfer the mail.

In our case of sending to a Microsoft address, the mail client submits mail to the Plusnet server which then stores and tries to send the mail to the Microsoft server. Why the Microsoft server differentiates on how the Plusnet server received the email from the originating client is confusing ? in fact I'm not even sure how it knows what client was used ? it requires examination of the headers from received email from both webmail and other clients

[#7]

Once again ...

MS Outlook via 123Reg and gmail.com  SMTP servers works to multiple destinations including to Live/Hotmail/Outlook
The same MS Outlook via Plusnet SMTP fails every time to all of the Live/Hotmail/Outlook destinations.

How simple does it have to be to see MS Outlook is not the root cause ?


Imagine if I'd written this light bulb works in the first two lamps, but fails to work in a third lamp.
How many think the bulb is defective ?

[#8]

What email addresses are you using to send from 123reg gmail.com?

[#9]

How simple does it have to be to see MS Outlook is not the root cause ?

I agree, MS Outlook is NOT the root cause.

The question I'm asking is why is (apparently?) mail sent (from a *.plus.com address) via the webmail client accepted BUT mail sent via other mail clients (including but not exclusively MS outlook) accepted ?

[#10]

@PhilipHeyes said:
"MS Outlook via 123Reg and gmail.com SMTP servers works to multiple destinations including to Live/Hotmail/Outlook
The same MS Outlook via Plusnet SMTP fails every time to all of the Live/Hotmail/Outlook destinations."

Are we getting confused here between (a) MS Outlook, the local email client on your computer. And (b) Outlook.com, the mass market server which receives emails sent to their customers with outlook.com email addresses?

The problem seems to be with (b), not (a). The mass market server at the far end is treating Plusnet emails differently from other senders, apparently because of the username.servername.com address format. That is a misconfiguration at the far end.

Live/Hotmail etc are in the same stable and evidently have the same misconfiguration.

[#11]

@Tim-J Thank you for pointing that out.

[#12]

We do not know that the Outlook email clients is not a significant contributing factor.

The root cause is indeed bulk sender designation of all *.plus.com users as being a single sender.  If the same designation is not applied to the 123reg configuration, then comparisons  between that and Plusnet are not comparable.

@MisterW 

Email headers identify the submitting client and the IP address.  Thereby it is easy for any receiver to profile emails by source, beyond the SMTP service.  There are lots of factors which could be guessed at as being the cause for observed outcomes; what is required here is for MICROSOFT to explain their behaviours.

The various email clients are not parts of the Plusnet supplied solution; webmail is and the reports here suggests that works as expected.  As you have observed in respect of an entirely different email service, DMARC reports indicate that DKIM failures due to time outs are rife, placing the issue squarely in Microsoft’s court.  That though is not what folks want to hear.

Question for those reporting the experience - are your email clients connected via Plusnet’s ISP service or a third party’s.

[#13]

Plusnet is my ISP.

[#14]

Virgin Media are our ISP.        Sub 2Mb/s ADSL is the only Plusnet option in our street.

We always use POP3 / IMAP / SMTP servers with Credentials & Encryption on in bound and outbound.

We always send using the correct email address for the providers email servers meaning :

<name>@<company>.co.uk   via 123reg the <company> domain host

<name>@gmail.com   via gmail

<name>@<account>.plus.com via Plusnet

[#15]

“The root cause is indeed bulk sender designation of all *.plus.com users as being a single sender.” Here, How to use DKIM for email in your custom domain - Microsoft Defender for Office 365 | Microsoft Lear..., Microsoft say “For email services that aren't under your direct control (for example, bulk email services), we recommend using a subdomain (for example, marketing.contoso.com) instead of your main email domain (for example, contoso.com). You don't want issues with mail sent from those email services to affect the reputation of mail sent by users in your main email domain.”

From that, I would infer that MS apply might different criteria when they see a native plusnet address (you@youraccount.plus.com) i.e. they treat it as a bulk sender on a ‘guilty until proved innocent basis’. In my earlier post #384 I relayed an IT friend’s opinion that when an email has come from Plusnet webmail, MS don’t see or don’t pick up on the subdomain element of the sending address and consequently a different threshold for rejection is applied and the email is accepted.

Last night I sent one email to a further 12 hotmail and outlook.com addresses via webmail with 0 failures.

“Question for those reporting the experience - are your email clients connected via Plusnet’s ISP service or a third party’s” – I am connected via Plusnet’s ISP.