Top tip: If your mailbox has recently been migrated to Office 365 – please first delete your existing email account before following the instructions below.
Tap Settings > Mail, Contacts, Calendars > Accounts > Add account > Email.
In the Add Account page, tap 'Exchange'.
Enter your full email address, for example email@example.com, and your password, and then tap Next.
The server settings will automatically be configured a this stage. By default, Mail, Contacts, and Calendar information are synchronized. Tap Save.
If you're prompted to create a passcode, tap Continue and type a numeric passcode. If you're prompted and don't set up a passcode, you can't view this account on your device. You can also set up a passcode later in your settings.
Top Tip: if the server settings are not automatically detected try disconnecting your device from Wifi and repeat the above steps. If this still does not work try turning your phone off first and then add your account.