To configure an Office 365 account for an iOS device, perform the following:
1. Open the device, and then tap the Settings application.
2. From the Settings menu, tap Mail, Contacts, Calendars.
3. Specify email type: click Exchange or Microsoft Exchange. **Note: If you have an old account configured in your device, remove it before adding the new service.
4. Enter your email address and password, and then tap Next.
5. Enter the exchange server information.
Domain: enter your domain name
Tap Next to verify settings.
6. Please wait while your device verifies the server settings. If this steps fails, double check server settings, retype password and try again. Tap Save to complete the setup.
A video tutorial of the configuration is available in the following article: