To add your hosted email address to your iPhone or iPad please follow these steps:
On your device open Settings, then scroll down and select Mail, Contacts, Calendars.
Select Add Account, then select Other. Next, choose to Add Mail Account. You will be prompted to enter your Name, Email, Password and Description.
Select IMAP for your mail server. Below you will be required to enter the Host Name (mail.domainname.com), Username (email@example.com) and Password for both the incoming and outgoing mail servers.
Incoming Mail Server: mail.domainname.com
Outgoing Mail Server (SMTP): mail.domainname.com
Incoming Port (IMAP): 143
Incoming Port (POP) : 110
Outgoing Port (SMTP): 25
Username: Your full email address
Password: Your password
Important: iOS may suggest that these fields are optional, however they are required when adding your hosted email. Please be sure to add your username and password for both mail servers.
Click Next to proceed. In the event that your port numbers do not automatically populate, use Incoming port 143, and Outgoing (SMTP) port 25.
Your hosted email address has now been configured to your Apple device.