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?