Hello,
We are in the process of setting up our exchange hybrid environment.
mail flows in almost any direction except from on prem to our 365 email accounts.
All email flows to 365 first (MX to outlook.com server)
I can send from 3<sup>rd</sup> party to on prem.
I can send from 3<sup>rd</sup> party to office 365
I can send from on prem to 3<sup>rd</sup> party
I can send from office 365 to 3<sup>rd</sup> party
I can send from office 365 to on prem
I CANNOT send from on prem to 365
The error I get when trying to send from on prem to 365 is -Remote Server returned '550 5.1.1 RESOLVER.ADR.RecipNotFound; not found'
I have tried 3 different send connectors - including a smart host I used for another company that does work for the other company - just not them. I also tried a smart host that MS suggested and that doesn't work - I don't think it is the send connector.
I tried changing the on prem normal domain accepted domain from authoritative to internal relay - same problem
I tried changing the on 365 default normal domain accepted domain from authoritative to internal relay - same problem