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

[#1]

@WorldMachine 

Following my earlier post ~ and just to bring me down to earth ~ an email sent to the same Hotmail account via my Plusnet/Classic Outlook account has just been bounced back !

Oh well, at least I have a means of reaching my few Hotmail contacts ~ via the Greenby/Webmail site.

[#2]

I am unsubscribing from this thread. I am in the process of moving my domain and email away from Plusnet and nowhere near Greenby.

If you are new to this thread may I suggest you read back through it. This problem is intermittent, years old and it seems Plusnet have not once committed to resolving the underlying issue.

Good luck.

[#3]

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@phil17 wrote:

..it seems Plusnet have not once committed to resolving the underlying issue.

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Tragically, I have to agree with that assessment.

@plusnettony is there ever going to be an end to this block by MS?

[#4]

Haven't bothered trying to chase this as it's obvious Plusnet/BT or even Greenby (pppfffttttttt) don't seem to have anywhere near enough clowt to get it resolved. 🤬

[#5]

 We can now send email to hotmail address with no problems - we moved to a non-Greenby email provider...

[#6]

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@balvack2 wrote:

...we moved to a non-Greenby email provider...

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Which is where I'll be going very soon.

Meanwhile, If anyone connected with Plusnet even vaguely cared about customer service any more, surely someone would say more about this block by MS.

Hello, testing, testing, @plusnettony @dave @Townman @MisterW...

[#7]

Just sent my  monthly mailing lists. I am gobsmacked that this still isn't fixed....! [-Censored-] are you playing at, PlusNet? This is beyond a joke now.

[#8]

My mother has been having this problem on her Force9 account for several weeks. She raised a call and I've just checked on the progress. The gist was that Plusnet's servers, and especialy the older relay.force9.net rather than the newer relay.plus.net have been blacklisted by hotmail and outlook. The support guy actually recommended contact Microsoft to get them to take Force9 off their black list - as if that's going to happen 😉

My tests have established:

- mail sent from an email client (Outlook) or from webmail.plus.net (username is in the form <username>+<mailbox, server Force 9) generate a rejection " Unfortunately, messages from [84.93.230.227] 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."

- mail sent by from webmail.plus.net using a plus.com address and server Plusnet do not generate an error; I'm waiting for confirmation from the recipient than the message has arrived

- mail sent from an email client (Thunderbird) from a plus.com address and server relay.plus.net do not generate an error; I'm waiting for confirmation from the recipient than the message has arrived

So, in my case anyway, the problem seems to be confined to mail sent from a force9.co.uk address using relay.force9.net - it looks as if that server's IP has been blacklisted but relay.plus.net's IP may not have been blacklisted.

Now I need to work out how to configure my mum's Outlook so it sends from relay.plus.net using a .plus.com user ID, while still receiving POP mail using mail.force9.net 

(The plus.com email address is an unused one which is associated with a new internet connection: the internet connection used to be via Force9, allied to the .force9.co.uk email address, but when my parents upgraded from ADSL to VDSL/FTTC, Plusnet had to create a new user ID (and hence allied email address) because they weren't able to keep the existing account but change the connection type from ADSL to VDSL. What a mess!)


It really is not acceptable that part of Plusnet's mail "space" (ie .force9.co.uk addresses and relay.force9.net STMP server) have been blacklisted by hotmail and outlook and Plusnet don't seem to be doing anything about it for those people who have not been migrated to Greenby.

[#9]

Has anyone else tried raising a complaint on this? I opened a ticket a few days back and got a very prompt but pretty generic reply, But today I got two e-mails with the same date and time stamp, one of which says

"Sadly, there has been no resolution date for a fix as of yet."
...and the other, which says:
"We believe we've now fully resolved your issue."

Hopefully one or both of these messages were generated automatically, otherwise it just make just sent my s PN's handling of this look even more silly.

However, by coincidence I just sent a group mail to several people on Hotmail addresses and didn't get a single bounce back. Dare I hope that it is actually fixed?

[#10]

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@Digsy wrote:

...Dare I hope that it is actually fixed?

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As the original poster, way back on 28th February 2026, I can report that my latest check on this problem is a convincing fail:

Reporting-MTA: dns; avasout-ptp-002 [84.93.230.235]
Received-From-MTA: dns; [redacted]
Arrival-Date: Tue, 14 Apr 2026 12:19:12 +0100


Final-recipient: rfc822; [myOutlookAccount]@outlook.com
Diagnostic-Code: smtp; 550 5.7.1 Unfortunately, messages from [84.93.230.235] 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=11BD332231205E75] [MWH0EPF000C618A.namprd02.prod.outlook.com 2026-04-14T11:19:13.323Z 08DE999119207FCC]

Last-attempt-Date: Tue, 14 Apr 2026 12:19:13 +0100

I expect @plusnettony @dave @MisterW @Townman to ignore this latest gripe from me as that's what they have done for most of my previous posts about this problem.

[#11]

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In case@plusnettony @dave @MisterW @Townman need more details, that delivery failure in my previous post was in response to a message sent:

From: [myPrimaryMailbox]@[myAccountName].plus.com

To: [myOutlookAccount]@outlook.com

Using: POP3 in Outlook 365 on Windows 11 Pro (both fully up to date)

with the outgoing server set to: relay.plus.net

'Require logon using Secure Password Authentication' is NOT ticked 

'My outgoing server (SMTP) requires authentication' IS ticked and under that 'Use same settings as my incoming mail server' is the selected option

The outgoing port number is 587 and the encryption is STARTTLS

[#12]

@stuck its not being ignored. I just dont have any more information.

[#13]

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@MisterW wrote:

I just dont have any more information.

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While that's not a step to towards a solution I do appreciate the feedback, so thank you for the response.

My own theory on how long it's going to take to fix this problem is not until the migration is complete AND Greenby have dealt with the spam storms that triggered this block by MS. So maybe in a year's time?

I'll be long gone by then, my PN broadband contract ends in July.

[#14]

@stuck wrote: I'll be long gone by then, my PN broadband contract ends in July.

Lucky you. Many Plusnet contracts will expire over the next year. It would be interesting to see how many long-time customers renew their contracts. Those who never used Plusnet email and did not have to endure the painful long march to Greenby will probably stay.

[#15]

Can't be ar$ed to read through 14 pages relating to this issue, but have just got this bounce from message to a single hotmail recipient sent 3 days ago. Never had any email problems with plusNet emails, to this same recipient but since the migration it has been shoite

Diagnostic-Code: smtp; 550 5.7.1 Unfortunately, messages from [84.93.230.235] 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=11BD2C9C659429B4] [BL02EPF0002992D.namprd02.prod.outlook.com 2026-04-14T07:24:54.034Z 08DE964E36D9158A]

Last-attempt-Date: Tue, 14 Apr 2026 08:24:54 +0100