You can find out by reading through reams of info on Office365.com or you can follow these simple steps…
- iPhone Settings\Mail, Contacts, Calendars\Add Account\Microsoft Exchange
- Fill in the fields with Username being your email address and leave Domain blank
- [If you get a 'Cannot Verify Server Identity" error then Continue], Next, Save
That’s it, you’re done. Let me know if you have any problems with that.