The following are the steps for setting up an IMAP email address on an Android Phone. It is possible that depending on the version of your Android Phone that some steps may be worded differently, but all of the versions we've tested have used the following settings:
1. Go to Settings on your phone.
2. Click to Email.
3. Click on Account Settings.
4. Click on one of the accounts.
5. At the bottom of the email settings page, there's the Incoming Settings, click it
6. Here you'll enter your username (firstname.lastname@example.org) and your password
IMAP Server: mail.yourdomain.com
Port Number is 143
Security Type: None
Authentication Method: PLAIN
IMAP path prefix: Leave EMTPY (it'll say Optional by default)
7. Click DONE.
8. Now lets click to the Outgoing Settings section.
SMTP server: mail.yourdomain.com
Security type: None
Require sign-in: Check this box
Authentication method: Plain