If you use Hotmail or Outlook.com for personal email, you may wish to add your account to your iPhone or iPad.
1) Tap SETTINGS, and then slide down to MAIL, CONTACTS, CALENDARS.
2) Press ADD ACCOUNT, and then select OUTLOOK.COM (Note that this setting can be used for Hotmail as well).
3) On the next page, fill in your Hotmail/Outlook.com email address, password, and a description, and then press NEXT. We recommend that you use your email address as the description.
4) On the next screen, you will see options for Mail, Contacts, Calendars, and Reminders all set to active (green).
5) Press SAVE.
Thanks to Ryan for cooking up this hint!