Hotmail rejecting mail from PN [Diagnostic-Code: smtp; 550 5.7.1]

[#1]

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@SteveA wrote:

Sill Broken

Last-attempt-Date: Wed, 11 Feb 2026 18:48:56 +0000

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Whereas also on Wed 11th a message I sent to a Hotmail address was delivered as expected.

Yet, today, a reply I sent back to the same Hotmail recipient bounced instantly:

messages from [212.159.14.20] weren't sent

@plusnettony how much longer is this email sending lottery going to continue?

[#2]

Okay, so not just me. I've just tried to reply to an urgent mail from someone using Hotmail, and I get this:

Diagnostic-Code: smtp; 550 5.7.1 Unfortunately, messages from [212.159.14.20] weren't sent. Please contact your Internet service provider since part of their network is on our block list (S3140). You can also refer your provider to http://mail.live.com/mail/troubleshooting.aspx#errors. [Name=Protocol Filter Agent][AGT=PFA][MxId=11BCCAE0B8EECE40] [SJ1PEPF000023D5.namprd21.prod.outlook.com 2026-02-13T07:28:23.283Z 08DE657062FE2321]

[#3]

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@plusnettony how much longer is this email sending lottery going to continue?

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This is unrelated to the project I'm working on, but I've asked around and it will get betters soon. I have no estimated time though.

[#4]

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@plusnettony wrote:

This is unrelated to the project I'm working on, but I've asked around...

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Thank you for trying to get an update.

[#5]

I set up an Outlook email account in readiness for my migration from Greenby and my test emails to xxx@outlook.com aren't going through with the same 550 5.7.1 error.  Furthermore, the bounce backs are going into my Greenby junk folder!  Methinks it is a conspiracy!!

[#6]

@plusnettony - Thank you for the update and providing (some) inside knowledge from PlusNet.

Although, emails from my PlusNet email (xx@yy.plus.com) are still being blocked/bounced by Microsoft - regardless of whether I send them via multiple BCC, multiple To/CC, or individual To.  They even get blocked if I reply to a direct (new) email from a Microsoft email address - which is crazy!  That person initiated email contact with me, but Microsoft won't let me reply to it!  I've resorted to using WhatsApp to send the (bounced) email content including attachments.  Only drawbacks are you need the mobile phone number of the user and I have to send individual messages (not group messages) to ensure phone numbers aren't made public (to the group).  But at least my messages don't bounce!

To be fair to PlusNet, I am getting regular (roughly weekly) updates from the Support Team - the latest of which is below:

I'm really sorry that this issue is ongoing. We will continue to liaise with the relevant parties, and update you further at some point next week. Kind regards

Admittedly, there is no (obvious) progress, but at least PlusNet are keeping me in the loop, and sounds like PlusNet are still trying to resolve the issue.

(Unlike Greenby - who customer service is awful.  The only way to contact them with an issue is to raise a ticket - which they nor their Chatbot respond to! And I can't find a phone number to call to speak a real human being!)  I am seriously considering swallowing my principles and going for a Gmail/Outlook email address.

[#7]

@LD289 

Just to be clear, it's nothing to do with how you are sending the email. It's entirely to do with the Plusnet server that is being used to send your email. Most, if not all of the outbound servers are currently on Microsoft's block list (and a few other providers!).

[#8]

Still zero progress.

This is Microsoft not accepting emails from Plusnet, the issue restarted
following a recent spam sending event from the Plusnet email platform.

Reporting-MTA: dns; avasout-peh-001 [212.159.14.17]
Received-From-MTA: dns; xxxxlaptop [86.30.96.254]
Arrival-Date: Sun, 15 Feb 2026 11:47:48 +0000


Final-recipient: rfc822; jxxxxxc@outlook.com
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 (S3140). You can also refer your provider to http://mail.live.com/mail/troubleshooting.aspx#errors. [Name=Protocol Filter Agent][AGT=PFA][MxId=11BCD7742FAEBC6A] [DS2PEPF000061C2.namprd02.prod.outlook.com 2026-02-15T11:47:48.947Z 08DE6BBA1883814A]

Last-attempt-Date: Sun, 15 Feb 2026 11:47:49 +0000

[#9]

Thanks

I wasn't aware of this; another nail in the coffin for Plusnet.

[#10]

Broken again

Final-recipient: rfc822; xxxxxx@outlook.com
Diagnostic-Code: smtp; 550 5.7.1 Unfortunately, messages from [212.159.14.20] weren't sent. Please contact your Internet service provider since part of their network is on our block list (S3140). You can also refer your provider to http://mail.live.com/mail/troubleshooting.aspx#errors. [Name=Protocol Filter Agent][AGT=PFA][MxId=11BCD75108F24857] [DS3PEPF000099DE.namprd04.prod.outlook.com 2026-02-17T13:17:35.025Z 08DE6BA886E49308]

Last-attempt-Date: Tue, 17 Feb 2026 13:17:35 +0000

and

Final-recipient: rfc822; yyyyyyyy@hotmail.com
Diagnostic-Code: smtp; 550 5.7.1 Unfortunately, messages from [212.159.14.20] weren't sent. Please contact your Internet service provider since part of their network is on our block list (S3140). You can also refer your provider to http://mail.live.com/mail/troubleshooting.aspx#errors. [Name=Protocol Filter Agent][AGT=PFA][MxId=11BCD755DB96CE41] [DS1PEPF00017091.namprd03.prod.outlook.com 2026-02-17T16:55:15.269Z 08DE6BAAF06F1B7A]

Last-attempt-Date: Tue, 17 Feb 2026 16:55:15 +0000

This is beyond a joke now

[#11]

And if you manage to not be blocked, you get a lovely 452 "too many recipients in the last hour" as I've just experienced (for the umpteenth time).

[#12]

@SteveA @Davidspeers @john_chandler 

Can you all clarify if you have been migrated or not?

I was plagued with 452 "too many recipients in the last hour" errors before migration in December, but have had none since.

[#13]

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@mavison wrote:

@SteveA @Davidspeers @john_chandler 

Can you all clarify if you have been migrated or not?

I was plagued with 452 "too many recipients in the last hour" errors before migration in December, but have had none since.

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At this moment in time we have not been migrated. I have this problem outstanding as a complaint. I'm hoping I've managaed to make alternative arrangements before I get dumped.

I do hope the staff, at the coal face, are being treated much better.

[#14]

Yes. I was migrated in December.

[#15]

I have no idea - never had an email about it happening, never had anything saying I have been. So probably not.