topic Re: Hotmail rejecting mail from PN [Diagnostic-Code: smtp; 550 5.7.1] in Email

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

stuck — Wed, 28 Jan 2026 15:43:55 GMT

Yet again part of the PN network is being blocked by Hotmail. This bounce just in...

Diagnostic-Code: smtp; 550 5.7.1 Unfortunately, messages from [212.159.14.18] 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=11BCB46066DEFB1C] [CH1PEPF0000A349.namprd04.prod.outlook.com 2026-01-28T15:16:16.472Z 08DE5A3038B8CCD0]

@plusnettony Any chance this block will be removed any time soon? Like within 24 hours? I need to be able to reach the recipient.

EDITED TO ADD: The message that was rejected was a simple one, no attachments, no links, and it was TO only one person, an @hotmail.com address

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

plusnettony — Wed, 28 Jan 2026 15:41:37 GMT

I'll need the from email address and I can do some checks. You'll need to PM it.

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

stuck — Wed, 28 Jan 2026 15:48:57 GMT

OK, done that.

Thank you!

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

PhilipHeyes — Wed, 28 Jan 2026 17:07:57 GMT

We are seeing the same rejections from Hotmail.

Reporting-MTA: dns; avasout-peh-002 [212.159.14.18]
Received-From-MTA: dns; hplaptop [86.30.96.254]
Arrival-Date: Wed, 28 Jan 2026 16:57:51 +0000

Final-recipient: rfc822; xxxxxxx@hotmail.co.uk
Diagnostic-Code: smtp; 550 5.7.1 Unfortunately, messages from [212.159.14.18] 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=11BCB35EDF918E76] [DB1PEPF000509F7.eurprd02.prod.outlook.com 2026-01-28T16:57:51.693Z 08DE59AF77F64DD3]

Last-attempt-Date: Wed, 28 Jan 2026 16:57:51 +0000

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

abitpedantic — Wed, 28 Jan 2026 17:24:59 GMT

Me too. An email just to one hotmail recipient, sent via avasout-peh-002. Was fine last night but not since at least 12.30 today.

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

Digsy — Wed, 28 Jan 2026 22:12:55 GMT

I am getting this as well, both from hotmail and icloud accounts but the error message doesn't tell me much:

This is an automatically generated Delivery Status Notification.

Delivery to the following recipients failed permanently:

* <deleted>@hotmail.com

Reason: A message that you sent to the following recipient could not be delivered due to a permanent error. ** The remote server ?? responded with: ** <deleted>@hotmail.com ??:?? This message was created automatically by mail delivery software on the server .

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

abitpedantic — Thu, 29 Jan 2026 09:49:32 GMT

@Digsy

Is there no attachment you can open that tells you more?

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

PhilipHeyes — Thu, 29 Jan 2026 17:00:32 GMT

Below are two Microsoft rejections one from a HOTMAIL destination and one from a LIVE destination,
these two rejecting recipients were on the same email as four other non Microsoft destinations which
all four have been delivered successfully.

Reporting-MTA: dns; avasout-peh-001 [212.159.14.17]
Received-From-MTA: dns; relaptop [86.30.96.254]
Arrival-Date: Thu, 29 Jan 2026 14:00:11 +0000

Final-recipient: rfc822; xxxxxxxx@live.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=11BCBE62645BE71A] [MN1PEPF0000F0E5.namprd04.prod.outlook.com 2026-01-29T14:00:12.581Z 08DE5F3132433EF5]

Last-attempt-Date: Thu, 29 Jan 2026 14:00:12 +0000

Reporting-MTA: dns; avasout-peh-001 [212.159.14.17]
Received-From-MTA: dns; relaptop [86.30.96.254]
Arrival-Date: Thu, 29 Jan 2026 14:00:11 +0000

Final-recipient: rfc822; xxxxxxxker@hotmail.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=11BCB30E667E7252] [CO1PEPF000075F3.namprd03.prod.outlook.com 2026-01-29T14:00:13.057Z 08DE59873AAF5FF9]

Last-attempt-Date: Thu, 29 Jan 2026 14:00:13 +0000

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

Digsy — Thu, 29 Jan 2026 21:39:11 GMT

@abitpedantic

Yes, there were three attachments, one of which was the original message and another which looked like just a list of the recipients (it was a group e-mail).

The third attachment is below:

Reporting-MTA: dns; avasout-peh-004 [212.159.14.20]
Received-From-MTA: dns; <deleted my IP address>
Arrival-Date: Wed, 28 Jan 2026 22:07:25 +0000

Final-recipient: rfc822; <deleted>@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=11BCB325D294832E] [BN1PEPF0000468A.namprd05.prod.outlook.com 2026-01-28T22:07:26.034Z 08DE5992F0318D5B]

Last-attempt-Date: Wed, 28 Jan 2026 22:07:26 +0000

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

Lordwotsit — Thu, 29 Jan 2026 22:07:01 GMT

Can I add to this please as we are getting rejections from Hotmail.com; Hotmail.co.uk; Outlook.com; Live.co.uk; Tiscali.com; as well as various BTInternet.com which we've been having for some weeks now. Also an odd one going to afriend@ZZZZZZZfamily.co.uk

The BT ones report 554 looks like spam. The Hotmail, etc are reporting 550 5.7.1 - (212.159.14.20) - Please contact your Internet service provider since part of their network is on our block list (S3140)

These are people we have been sending emails via BCC for a long time, years, now ever since the impending migration we have been getting rejections because some(one/thing/computer) thinks we're now suspected of sending spam mail.

I can assure you - WE ARE NOT SENDING SPAM MAIL - all the people we have in our distribution list have asked us to keep them informed.

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

stuck — Fri, 30 Jan 2026 11:25:34 GMT

@plusnettony wrote:

...I can do some checks...

Please can you update the now several users reporting this same problem. What was the outcome of your checks?

Do you have an update on when the blocks on these PN servers will be lifted?

Thank you.

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

LD289 — Fri, 30 Jan 2026 15:46:46 GMT

I also had the same issue on Wednesday - and I raised a "complaint" with PlusNet. I've acknowledgement from PlusNet Support (via email) of the issue, which said they have passed this onto the Network Operations team, and that PlusNet Support will get back to me next week.

I've had the same issue today - when sending to multiple Microsoft email addresses (xx@hotmail.com, yy@hotmail.co.uk) via BCC and when sending to individual Microsoft address (in the To:line)

I send out communications to over 100 email addresses (as a volunteer) on behalf of a local sports club - and this "blocking" is causing issues, as I cannot contact a number of club members (not even when sending them a individual email). Some members get important information - others don't! Any workaround suggestions gratefully received, and obviously a permanent solution from PlusNet would be even more appreciated.

Email Response

Delivery to the following recipients failed permanently:

* xx@hotmail.com

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

Reporting-MTA: dns; avasout-peh-001 [212.159.14.17]
Received-From-MTA: dns; DESKTOPVONN0ET [31.125.34.73]
Arrival-Date: Fri, 30 Jan 2026 14:49:52 +0000

Attachment - details.txt
Final-recipient: rfc822; @XX@hotmail.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=11BCB2EF70B9D4F9] [BL6PEPF0001AB58.namprd02.prod.outlook.com 2026-01-30T14:49:53.214Z 08DE5977C0FC5345]

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

Lordwotsit — Fri, 30 Jan 2026 16:49:57 GMT

@LD289

I too have rasied it as a complaint. The poor guy on the phone at CS politely listened as I berated of PN Senior Management. These problems must stem from the decision to dump it's email and website service.

Anyway, I do hope that the NW Ops Team are at this very moment telling their bosses that this is what is needed and that it will be resolved quickly!

@stuck

I wonder just how many users are suffering?

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

PhilipHeyes — Fri, 30 Jan 2026 17:39:15 GMT

This afternoon we had a spam message that is from a <name>@<account>.plus.com sender.

Perhaps you also have seen a fake security message claiming to be from Plusnet. It was not scored as spam.

These spam storms from Plusnet accounts are not new, nor is the deep email sender reputation damage they cause.

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

Lordwotsit — Fri, 30 Jan 2026 18:19:45 GMT

@PhilipHeyes

That's true.

However, what is the point of having "white lists" if the higher level server says "Nope, I'm not even going to send the persons Junk folder"?

That's what is happening to lots of my recipients.

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

Needing_help — Fri, 30 Jan 2026 21:22:44 GMT

Hi,

I'm new to this forum but having exactly the same problem: namely an email I send from a plusnet address to a hotmail address is being consistently rejected with the 550 5.7.1 error message. I get the same problem even with a single addressee and no attachment.

What's the best way forward please?

Many thanks!

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

Digsy — Fri, 30 Jan 2026 22:07:59 GMT

Just as an aside, given the amount of spam I have been receiving from PlusNet e-mail addresses over the last few days I'm not really surprised that we have got on Hotmail's blacklist

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

Lordwotsit — Sat, 31 Jan 2026 00:09:10 GMT

Here's a thought... are they actually coming from PN or are they coming from Greenby? All these problems seem to have started in the last twelve months or so. Coincidence!?

Anyone care to offer proof either way?

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

jab1 — Sat, 31 Jan 2026 08:00:04 GMT

@Digsy wrote:

Just as an aside, given the amount of spam I have been receiving from PlusNet e-mail addresses over the last few days I'm not really surprised that we have got on Hotmail's blacklist

Except, they are not coming from PN's servers, rather Amazon's AWS.

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

jab1 — Sat, 31 Jan 2026 08:00:37 GMT

@Lordwotsit wrote:

Here's a thought... are they actually coming from PN or are they coming from Greenby? All these problems seem to have started in the last twelve months or so. Coincidence!?

Anyone care to offer proof either way?

See above.