Step 1: If it's your first email account on your iPhone 4, click Mail. Otherwise, click Settings - Mail, Contacts, Calendars - Add Account.
Step 2. Click Microsoft Exchange.
Step 3. Click into Email box and enter your full email address. Then Click into Username box and enter your full email address too.
Here we offer you Set Up Outlook POP or IMAP Email Address on iPhone 4 Tutorial.
Step 4. Click into the Password box and enter your password.
Step 5. You can choose to enter a short description for the account in Description box. If you don't, it's ok!
Step 6. Enter IMAP or POP.
Step 7. Click in the Server box and enter m .outlook.com.
Step 8. Then Save.