1. Select the Settings Icon from your iPhone home screen.
2. Select Accounts & Passwords.
3. Select Add Account...
4. Select Other
5. Select Add Mail Account
6. Type in your email address and password and description.
7. Select IMAP, then fill in your email address & password and the server information for INCOMING / OUTGOING SETTINGS.
You need to complete all fields.
8. When attempting to verify you "may" receive the message "Cannot Connect Using SSL - Do you want to try setting up the account without SSL?" If you do, then select YES. After a few seconds you will receive the exact same message, select YES again. After the 2nd time you will get all check marks and you'll see the following image.
9. Mail should be set to ON and Notes should be set to OFF, Select Save
10. Congratulations you have successfully setup your mailbox to use IMAP on your iPhone.