SMTP error 550 5.7.1 part of network is on block list

ebforum · ‎05-01-2022

I have received this bounceback on sending an e-mail from Outlook 365 on my PC using my Plusnet e-mail account to an Outlook.com recipient.

Part of the network on their blocked list?

Reporting-MTA: dns; euk22.eukhosting.net

Action: failed
Final-Recipient: rfc822;xx@yy.org.uk
Status: 5.0.0
Remote-MTA: dns; outlook-com.olc.protection.outlook.com
Diagnostic-Code: smtp; 550 5.7.1 Unfortunately, messages from [nnn.nnn.nnn.nn] 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=11BC29117274DD8A] [DS1PEPF0001709C.namprd05.prod.outlook.com 2025-10-29T11:01:47.997Z 08DE1488BC5141F0]

Leanne_T · ‎10-12-2024

Morning @ebforum

Thanks for starting a new thread for the email error message.

I've received the reply to my private message this morning and I will send the details to the relevant team for investigation.

Thanks

Leanne.

Townman · ‎22-08-2007

When they provide a remedy, can you please post back to here what it is, so that future occasions users are informed of the appropriate actions.

In another browser tab, login into the Plusnet user portal BEFORE clicking the fault & ticket links

Superusers are not staff, but they do have a direct line of communication into the business in order to raise issues, concerns and feedback from the community.

If this post helped, please click the Thumbs Up and if it fixed your issue, please click the This fixed my problem green button below.

abitpedantic · ‎31-07-2025

Presumably this is a different issue from the severe blocklisting that was occurring for many weeks until about 2 weeks ago when it seemed to be resolved and Microsoft-owned addresses could be reached again. Has there been another outbreak of spam?

I note that, unless the sequence of n’s has been mis-typed, the blocked server is not a Plusnet avasout one, assuming their IP addresses haven’t changed (they were 212.159.14.nn and 84.93.230.nnn).