Set up an Office 365, Exchange, or Outlook.com email in the iOS Mail app
Go to your iPhone or iPad's Settings > scroll down and tap Accounts & Passwords > Add Account.
Note: If you're on iOS 10, go to Mail > Accounts >Add Account.
Enter your email address. Tap Next.
Tap Sign In.
Enter your credentials. Tap Sign in
Choose the services you want to sync with your iOS device and tap Save. You're done!