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

[#1]

Not fixed for us, this morning we have seen 3 different Microsoft emails and one iCloud all rejecting PN servers.

[#2]

Still bouncing! 😒

[#3]

Yup, still bouncing.

@plusnettony you have already told us that this is out of your scope but you did at least previously try to poke the relevant people on behalf of us poor users.  Please, please, please can you ask again and tell us what response you get?  Even if that reply is along the lines of, "Ha ha ha, this problem is never going to get fixed."

[#4]

Can you send me some bounce backs of the IP that's being hit ( I believe it's less than it was) so I can try to get some traction?

[#5]

Is this of use? My bounceback this morning: (I've removed the final recipient, which was an outlook.com address)

Reporting-MTA: dns; avasout-peh-001 [212.159.14.17]
Received-From-MTA: dns; mail.enmail.co [91.204.208.8]
Arrival-Date: Tue, 24 Feb 2026 09:36:45 +0000

Final-recipient: rfc822; [removed by me]
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=11BCD8B077DDFA86] [CY4PEPF0000E9D7.namprd05.prod.outlook.com 2026-02-24T09:36:46.329Z 08DE6C58447FB3CC]

Last-attempt-Date: Tue, 24 Feb 2026 09:36:46 +0000

[#6]

212.159.14.17   rejected by Microsoft
212.159.14.20   rejected by Microsoft 

84.93.230.227   rejected by iCloud

[#7]

212.159.14.17 Outlook bounceback.

Thanks

[#8]

Attempting a test for @plusnettony I have just managed to successfully send an email to my hotmail contact for the first time in days. However, any subsequent email I have tried to any address gets the old error:

SMTP Error (452): Failed to add recipient XXXX recipient rejected - too many recipient in last hour

Funny old game. I'm moving as soon as I get some time. Thanks for the Mythic Beast tip earlier on this thread. Looks good.

[#9]

Thanks all, thats going to be really helpful. 

I'm going to get asked for full bounces, so if you PM them, I will see if I can get it pushed forward tomorrow when I've got them all. 

I appreciate the list of the actual servers too. 

[#10]

@plusnettony I deleted the bounce that prompted my post earlier today so I've just tried to generate a new one.  However, this latest message didn't bounce. Even so I doubt that means the problem has been fixed.  I'll test again tomorrow and report back.

Meanwhile, my earlier message that bounced was sent from [me]@[accountName].plus.com to my @outlook.com address using my Outlook (classic) MS 365 client configured to use POP3 from my Win 11 desktop PC.  The offending server was 212.159.14.17.

The message of a few moments ago that didn't bounce was sent using webmail.plus.com accessed using latest version of Firefox running on my Win 11 laptop.  In the headers of the delivered message I read: 'sender IP is 84.93.230.244'.

[#11]

Thanks for all the examples. The examples have been sent to the incident team - an incident is open. 

[#12]

@plusnettony 

I'm not getting at you personally, I can see you're doing your best, but why do you have to keep asking the users to provide examples of emails being bounced, for you to forward to the incident team? It should be obvious to Plusnet from their own monitoring which outbound servers are on which blocklists and they should be ahead of the game.

I gather that even after migration to Greenby, outgoing email is going via Plusnet’s servers for the foreseeable future. Is this because Greenby don’t have servers available or they are declining to deploy them for fear of them immediately becoming blocklisted due to the ongoing problems that, for once, are not of their making?

[#13]

I totally get where you're coming from, but I don't want to take the chance of any issues being rejected due to lack of examples. In my details, before the examples, I made it abundantly clear which IPs were problematic. 

[#14]

If I was wishing to automate blocking an ISP's emails, I'd block all the outgoing mail servers from the ISP's SPF lists.

[#15]

Another day, another load of bounces. Individual emails, Bcc Distribution list emails.

@plusnettony 

As others have said you are probably trying your best to move this problem towards being fixed.

My feeling is that Plusnet are just "kicking the can down the road" and eventually we'll all have gone.