Exchange Online Not Receiving from Only One Domain

Copper Contributor



We have migrated one service provider mail eg ( to M365. 

Exchange Online can be received from other external domains but can't receive from only that one service provider mail (

I traced mail flow from exchange > not received from ( but outgoing is ok.


Is there any way to track mail flow to prove Exchange Online is not received from that mail service provider (


M365 to is ok.

Online to M365 is not ok.



2 Replies
best response confirmed by zwethuko (Copper Contributor)
You probably have some traces left of your domain/recipients with the previous provider, check things on their end or open a case with their support.
Yes, bro, I'll check with their mail host provider.