To edit or update an existing email account with IMAP settings on an iPhone, iPad, or other iOS device take the following steps:
1. From the Home screen, tap Settings.
2. Tap Mail, Contacts, Calendars.
3. Tap the description of the Mail account to update.
4. Next to Account, tap the email address.
5. Update the account-specific Email settings obtained from the article linked above.
Tap Done if no further changes are required.
For additional incoming settings scroll down and tap Advanced.
6. Update the incoming settings as needed.
Choose your preference for Deleted Messages.
Tap Account to return to the previous screen.
7. Tap SMTP to update the outgoing mail server settings.
8. Tap the Primary Server. The primary server should match the SMTP server obtained from the Customer Portal.
9. Update the outgoing mail server settings as needed.
Authentication should be Password.
Tap Done to return to the previous screen then tap Account.
10. On the Account screen tap Done to verify the account settings.