Emails not be received from one domain

[Stew123]

Emails from the domain of a company I work with are being turned back as of two days ago - other emails are arriving.

I have no filters and no blocked accounts. 
the Sky help page link about "blocked domains"  says "page missing" so that's useless. 
I

[Stew123]

This is the error that their Microsoft service gives : 

 

[jayach]

There have been quite a few problems with receiving email from Microsoft domains recently.

Unfortunately, as far as I know, no one has been able to explain it,

It's always the same error message "email system didn't respond".