Exchange Mail Flow & Domains

[jamesky]

Hi guys, I hope you are all keeping well and safe.

I have a small challenge with my exchange, I hope to get some help here.

This is my situation.

I have 3 domains D1 (primary domain), D2 and D3 all added on Microsoft exchange under one account. D1 has its mailbox on Exchange whereas D2 and D3 their mailboxes are on host-gator servers.

For pilot test, I licensed several users on D1 since its the primary domain.

Now, when I send email from D1 (primary email) to D3 am getting bounce back.

Another case: When I send from D1 to D2 am not getting bounce back but they are not getting delivered on the other side.

What could be the issue?

[#2]

You need to set the domain intent for said domains to Internal relay: https://docs.microsoft.com/en-us/exchange/mail-flow-best-practices/manage-accepted-domains/manage-ac...
Otherwise Exchange will try "internal" delivery and fail unless a matching recipient is found. And you will probably also need to configure connectors to ensure proper mail flow to the host-gator servers.

[#3]

Thanks for your reply @Vasil Michev. I have set the domain intent to "internal relay" and created a connector. Still emails send from 0ffice 365 to my server are not being delivered but from my server to office 365 account are being delivered.

[#4]

Details are important, otherwise we can only guess...
Also run a message trace, it will give you a clue how a given message is being routed: https://docs.microsoft.com/en-us/microsoft-365/security/office-365-security/message-trace-scc?view=o...