Have you got a list of leads, potential customers, or existing database of people and want to identify or target those that are using Office 365? I can think of one or two scenarios where this would be handy!
Microsoft have a free modern Excel Add-in called “MX Lookup” (available in the Office Store) that takes a list of email addresses and will perform a lookup for each email address and will tell you if the backend mail system is Office 365 or not. Pretty handy right?
I’ve been using this add-in in demos and have recently noticed that it now identifies Outlook.com accounts as being Office 365 (where it originally identified these separately) so be aware that you may get a mix of Office 365 and Outlook.com users.