I have a customer who is adopting Office 365 – but in a targeted manner for certain parts of his business. The business case just doesn’t stack up for a total deployment but he does want to make the most of the features and functionality that are available, to showcase how it really can be used to those who are on the platform.

Because his email is still on the corporate mail platform (where the MX records point), and there is no Exchange hybrid connectivity configured, we’ve been looking at the use of connected accounts in Office 365 – so that certain key members of staff can use Exchange Online mailboxes without actually migrating their email service.

It’s an unusual scenario, and generally only mentioned as a quick and dirty solution to get people using Office 365 in pilot.  Even so, there’s no reason why it shouldn’t work for a more permanent solution – provided that the on-premises mail server can be reached from the Internet using POP3 or IMAP4 (preferably secured with SSL) and that it’s well-understood that Exchange Online will poll for new mail less frequently than a direct connection from Outlook to the source mail server would.  It’s also useful for pulling email from third party mail platforms into your Exchange Online mailbox (I use it for Hotmail).

The latest advice from Microsoft on using the feature can be found in the connect email accounts in Outlook on the web Office support page and there’s also some useful information on connected accounts in the Office 365 community.