What is the best way to allow delivery of messages to distribution list only from certain domains?

[MichalKar]

Hi,

I have a distribution list on O365 that is expected to accept messages only from 30+ domains (not individual addresses, but all addresses from listed domains *@domain.com, etc.). All other messages should be rejected. What would be the recommended way to achieve it?

best regards,

Michal

[#2]

Create a mail flow rule to restrict messages to said DL, and add exceptions for all domains in question.