Conversation

So ... my mail server greylists an incoming email.
The sending server re-queue's the message, but from a different domain.
So ... my mail server greylists that one as well.
rinse, repeat ... ( 5 times so far, that's 5 different relay domain names for the same message)

BTW the sending servers are #microsoft "mail-xxxxx.outbound.protection.outlook.com"

*sigh*