We help IT Professionals succeed at work.

Can I use Office365 e-mail to a subdomain while keeping my hosted IMAP in the primary domain - requires multiple MX records?

Lew Nix
Lew Nix asked
One of our company entities is currently using the hosted IMAP e-mailed provided for free as a part of their website hosting account.  I really want to move them to Office365, but the price difference - from "free" to $$$ - is making it a hard sell.  The companies has a group of employees - 30-40 - that really can get by with the IMAP hosting.  Another smaller group of 10 or so employees would really benefit from the features of Office365 hosted e-mail.  My thought is keep email to @mydomain.com pointing to the IMAP server via its MX record.  Setup Office365 to a subdomain @admin.mydomain.com and have its own MX record setup.  This seems possible, but I don't exactly know how Office365 setup will go in a subdomain.  Also, If I setup Office365 in this subdomain environment, would it be possible to move it to @mydomain.com if we ever reached a point where we were OK with paying for O365 subscriptions for all of the users?
Watch Question

Network Administrator
I don't see anything wrong with your idea.  The MX subdomains should work fine; people just aren't used to having that type of email address.

It's all DNS so as longs as O365 lets you set up the subdomain you should have no problems.  This KB might help for that:


To answer the second part of your question, you may need to do an export to PST and import into new mailboxes