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

[#1]

I've just had exactly the same rejection for an email to a hotmail address. Same server avasout-peh-004 and of course sending as plain text makes no difference in this situation.

[#2]

So, a few more days have elapsed and all has gone quiet again. Has there been any progress with the Microsoft-related email issues (DKIM failures and blacklisted Plusnet servers)?

[#3]

I have heard nothing more.  I’m still seeking updates; we need Microsoft be transparent about the issue / reasons for the seen experience.

[#4]

@Townman

It would help if Plusnet were more transparent too. Despite all your escalations and seeking updates there has not been any useful feedback from our email provider since mid-July even though the already bad situation is now deteriorating further.

It seems to me that the slogan "Plusnet - we'll do you proud" is fast becoming "Plusnet - we'll do you in".

[#5]

Yep I'd like to chime in with exactly the same problem as others, I also cannot connect to email servers that are part of my plusnet "sub" email addresses however i can connect to the primary one?!

Hope this gets solved quickly, i see its been dragging on for some time, as the Darleks would say:-

ESCALATE,  ESCALATE,  ESCALATE!!!

[#6]

I'm getting the same message when sending single personal emails to <name>@outlook.com.

I've had to use Gmail as an alternative.

Diagnostic-Code: smtp; 550 5.7.1 Unfortunately, messages from [212.159.14.17] weren't sent. Please contact your Internet service provider since part of their network is on our block list (S3150). You can also refer your provider to http://mail.live.com/mail/troubleshooting.aspx#errors. [Name=Protocol Filter Agent][AGT=PFA][MxId=11BBC4FF1616F6DA] [BN1PEPF00005FFE.namprd05.prod.outlook.com 2025-08-29T10:48:03.061Z 08DDE27F90178942]

[#7]

An observation...

The reject message from Microsoft may vary depending on :

1) the email being for single MS destination where : SMTP server on a block list is given.

2) for multiple destinations including one or more MS destinations where : Dkim= Fail is / are given

We have seen both scenarios of rejection for mails sent via SMTP server : avasout-peh-004 [212.159.14.20]

The SPF files for our <account>.plus.com emails list a total of 13 SMTP server IPs, we have recent reports
of two SMTP IPs on the MS block list and a third SMTP IP on the TalkTalk block list. 

With other ( perhaps all given our 100% failure rate  ) SMTP servers failing to deliver to multiple destinations where one or more MS destinations are present.

[#8]

Hi Philip,

Thanks for your points.

I have received the "Dkim= Fail" error also, but the messages now receive "block list" responses. In each case they are personal messages to single @Outlook.com addresses, not business emails to multiple addresses.

[#9]

Hi all,

I am only watching this out of professional interest now.

I cannot believe this is continuing with no resolution in sight after so many months,

I just feel sorry for the poorPlusNet users who cannot rely on their email service.

[#10]

@solodchin  Just a little bit of information for you, which may (or may not) explain PN's difficulties with M$/Google. For the past four months or more, I have been plagued with spam originating within  Googlegroups accounts. I  have consistently reported them, and eventually the group is closed, However, within days, hours even, the same group has resurfaced - under a different ID, but clearly the same, based on the spam style, and the route(s) they take to hide their identity.

Google obviously don't mind spam emanating from themselves.

[#11]

Jab1,

What is your game here ?

Clearly you do not have this problem.  

If you did your posts of delivery rejection errors and comments of very deep frustration would be here to read.

[#12]

No 'game', @PhilipHeyes . True, I do not have the M$ (or Google) email issue, as I only have one regular Gmail contact, which doesn't appear to have an issue,  when sending to me, or me replying, but they also have alternatives they could switch to if needed.

What I am trying to point out is that sorting the issue is not as simple as some may think, and it appears Google has double standards - I can't and won't comment on the Microsoft issue as I don't (now) have any contacts using M$ accounts.

The post you are referring to is admittedly nothing to do (directly) with the problems being experienced by you and others, but it does raise a few questions.

[#13]

@solodchin 

Do you have evidence to offer which supports your suggestion that this is a problem with the Plusnet mail platform … and not Microsoft’s?  The reports of variable DKIM processing in Microsoft space is legion.  Just Google it.

[#14]

@Townman 

@solodchin used the word “service” not “platform”. To my mind “service” includes keeping customers informed of progress on resolving problems, which Plusnet have completely failed to do. It’s no help saying that the problems have been caused by Microsoft, we deserve to know how the Plusnet team is progressing in getting them resolved. Even if they are banging their heads against a brick wall, it would be nice to know that they are at least sharing our pain!

[#15]

Are you personally regularly attempting to send to multiple Microsoft addressees and encountering failures?  The standing advice from the business is to send to individual addressees … that might be a tad inconvenient, but hardly “pain”.