On your device click on the Start button on the phone then Select Messaging, it might be on the dropdown or under Programs then Tap
Click the menu button select Option ( if you need to delete an account select delete)
Tap on New Account
E-Mail: Enter your email address
Password: Enter your password
Select Next
Uncheck Try to get e-mail settings automatically from the Internet Select NEXT
Select Your e-mail Provider : Internet E-mai from drop down menu
Select Next
Enter your full name
Change Account display name if you wish it to show up as
Select NEXT
Incoming mail server : mail.yourdomainname.com (be sure to set this to your domain name)
Account type : IMAP4 (very important to change from POP3 to IMAP4 for your mobile device)
Select NEXT
Username : enter your email address (This is your Full Email Address)
Password : Enter your password
Select NEXT
Outgoing SMTP mail server : mail.yourdomainname.com (be sure to set this to your domain name)
Outgoing server requires authentication : CHECK
Use the same username and password : CHECK
Select NEXT
Automatic Send/Receive : Manually
If you set this value to automatic it will use more battery life, this is up to you.
Select Review all download settings
Select NEXT
Select FINISH