– Start up Mail.app
– Go to File->Add Account. The account setup utility will appear.
– Enter your name for the account, and the e-mail address and password of the account you wish to add. Click Continue.
– Choose the IMAP e-mail server type.
– Next enter the incoming mail server (mail.yourdomain.com). This server is for receiving incoming e-mails. Also authenticate by entering the user name and password for that specific account. Click Continue when done.

– Next, enter the information for the Outgoing mail server (mail.yourdomain.com). This is for sending out mail. Also check use authentication and enter your user name and password once again as you did before. Click Continue and then click Finish.

Please confirm that the following settings are correct as well:

-Go to Mail > Preferences
-Go to Accounts and choose the IMAP Account
-Choose Advanced
-Clear the IMAP Path Prefix
-Close the Preferences Window and make sure to hit Yes to the save question