Please contact your Internet service provider since part of their network is on our block list

alastair3 — Thu, 19 Feb 2026 14:30:53 GMT

This seems to happen after a period of weeks currently. Webmail can send fine and after ringing up the help desk, that is all they are responsible for, so it's not an issue.

What I do not understand is why my mail service is reliable for months on end and then starts playing up. This is the 3rd time it has happened. Always when sending to Microsoft owned mail services.

Any ideas?

Re: Please contact your Internet service provider since part of their network is on our block list

stuck — Thu, 19 Feb 2026 14:54:31 GMT

See this topic, started three weeks ago, does it cover what you are asking about?

https://community.plus.net/t5/Email/Hotmail-rejecting-mail-from-PN-Diagnostic-Code-smtp-550-5-7-1/td-p/2035800

topic Re: Please contact your Internet service provider since part of their network is on our block list in Email

Please contact your Internet service provider since part of their network is on our block list

Re: Please contact your Internet service provider since part of their network is on our block list