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

[#1]

@mavison - I've not been migrated, as far as I can tell. Everything I know about the migration process has been from this forum, Plusnet have never sent me anything directly.

[#2]

@john_chandler 

That explains why you are still getting some  452 "too many recipients in the last hour" errors.

[#3]

I do not understand how the "too many recipients in the last hour" fails be applied
and repeatedly allows for spam senders that deliver tens to hundreds of thousands of junk emails
resulting in Microsoft, iCloud and Talk Talk / Tiscali slamming the door closed the entire customer base.

[#4]

I am also getting this failure to deliver to a hotmail email address - a single recipient, no attachments, was working yesterday. Please can a Plusnet employee let us know when this will be sorted.

Reason: A message that you sent to the following recipient could not be delivered due to a permanent error. ** The remote server ?? responded with: ** [recipient-email@hotmail.co.uk] ??:?? This message was created automatically by mail delivery software on the server .

Reporting-MTA: dns; avasout-peh-001 [xxx.xxx.xxx.17]
Received-From-MTA: dns; [192.168.1.xxx] [xxx.xxx.xxx.24]
Arrival-Date: Thu, 19 Feb 2026 14:59:00 +0000

Final-recipient: rfc822; [recipient-email@hotmail.co.uk]
Diagnostic-Code: smtp; 550 5.7.1 Unfortunately, messages from [xxx.xxx.xxx.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=xxxxxxxxxxxxxxxx] [server-details 2026-02-19T14:59:00.357Z xxxxxxxxxxxxxxxx]

Last-attempt-Date: Thu, 19 Feb 2026 14:59:00 +0000

[#5]

Am having same issue as well as Hotmail/Outlook failing to recognise valid email addresses and rejecting emails. 

[#6]

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@plusnettony wrote:..I've asked around and it will get betters soon. I have no estimated time though.

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Please can you ask around again as, disappointingly, it's not got better soon.

[#7]

The Boots spam sender is back and once again the message header shows the IP and domain name
of a Plusnet customer account and sending via the Plusnet email platform.

I fear more spam sending takes us even further away from a solution to ISPs and email operators putting a blanket block on emails from the Plusnet email servers.

[#8]

I had a brief window last night where one email got through to a Hotmail address, but this morning I'm back to getting bounce-backs again. The same S3140 block from Microsoft.

I can see PlusnetTony is active on the forum answering other queries, so I know staff are here. It's incredibly frustrating to see other issues being addressed while this ongoing email problem remains unresolved. With Plusnet moving away from email services, I understand priorities shift, but in the meantime those of us still relying on it are left with a broken service and no communication about when it might be fixed.

[#9]

@PhilipHeyes Have you forwarded the email to 'abuse@plus.net' so they can shut the abused account?

[#10]

@PhilipHeyes 

Please can you explain this to me.

Are you saying there is an identifiable spammer causing this?

In which case surely it is trivial for Plusnet to stop?

Thank you.

[#11]

Morning @jab1  already sent along with a full copy of the message source / header showing all the detail.

[#12]

@phil17 there is an identifiable Plusnet account and email that is shown as the sender.

That customer's account or perhaps compromised computer / server etc could be involved.

It would be a step to far to suggest that the customer is responsible for the sending the spam.

Especially as each time this occurs a new customer's account appears as the sender.

I've expressed my view on the need to secure relay.plus.net with credentials
and encryption for all email senders, but on that topic there is only silence. 

[#13]

I find it incredible that relay.plus.net is still insecure after all this time, so no wonder there are problems. I'll also join in and say that it's more likely to be someone exploiting the system than the customer themselves.

[#14]

Thanks very much, I think I understand:

The issue is likely that spammers are abusing connections from Plusnet's network (possibly through infected customer devices), and the fix would involve tightening authentication requirements for connections coming from a Plusnet internet connection. But presumably because Plusnet is winding down its email service, they're not investing into fixing it. Is that the gist of it?

If so, I have to say this is deeply frustrating. Email isn't a nice-to-have. It's an essential service. Plusnet took customers' money for years based on the promise of a reliable service. Choosing to let it decay rather than support it properly until the transition is complete feels like a breach of that trust.

Surely there must be some resource available to keep basic email functionality working? @plusnettony please respond.

[#15]

Just submitted today's second  "Boots" spam email & the message source / header to abuse@plus.net

A different Plusnet IP, Customer domain & Email address are seen this time,
but the generated style of the spam message is identical to what was seen earlier.