Learn how to add a custom mailbox to your hosting account:
To create a mailbox, log into the pair Account Control Center. On the left-hand side, click E-Mail and then Create New Mailbox. Enter in the username, followed by the domain name in the drop-down menu, entering the password twice. If you want to maximum mailbox size, click on the checkbox here and then select the Junk Email Filtering option.
When you are ready, click on the button below that says Add Mailbox. At the top of the page, in the green bar, it will state that your mailbox has been added, however, it may take 10 minutes for that mailbox they become active.