Office 365 with multiple domains in Office 365

Occasional Contributor

Dear community! 

I am new in Office 365 Exchange implementation.
I have my own domain and my own hosting on one server, where I have also my own emails, and I am running there via IMAP. On that mail server, I have many user email accounts. Now I am thinking of office 365 Exchange implementation, but only for 5 users first. 

My question is if I will be able to use also those email accounts from my own mail hosting after office 365 exchange implementation?

Is this option also available?

15 users from my old hosting, and 5 users from the exchange, where I need to have the same domain name.

Thank you for your replies.

Best regards,



11 Replies
Yes it’s called exchange hybrid. You keep mail flowing to existing servers and then a connector basically transfers the office 365 email to the mailboxes there. You can freely move mailboxes back and forth if correctly Setup.
Just to clarify! Do you have exchange server on premises, and if so what version ?


Hi, this is my DNS configuration now on my hosting, where I already add the required office 365 settings, but with this configuration file, the IMAP connection for the other users won't working. Only a few new outlook 365 users are working.
@INTXT"v=spf1 a mx ~all"


Maybe I did something wrong, or this kind of solution is not possible. I don't know.

Can you help me?

Thank you so much.


Best regards,


You transferred the domain correctly? You can do a dns test from the admin portal also!

I did the DNS test, and I don't have any error. Office 365 is working perfectly, but the other email accounts, which are not in exchange, they are not working. Technically, they not receiving anything.

That’s cause you changed the mx to 365!
Change back and do a hybrid or migrate!


thank you so much. i will try

but how to do that? What should is set up on both side?

We need to know more information about your environment ‘
We need to know more information about your environment! PleSe let us know your server version, etc