Configure iOS mail app for Office 365
Set up email using the iOS Mail app
Go to your device's Settings, scroll down and tap Mail > Accounts > Add Account.
Enter your full email address. Tap Next.
Enter your email account's password. Tap Sign In.
You may need to approve certain permissions such as accessing your calendar and contacts. To agree, tap Yes.
Choose the services you want to sync with your iOS device and tap Save.
Now you're all set to go!