Log in to https://controlpanel.hostedservices.com using your Admin Username and Password.
Click on Mailboxes.
Click on the display name of the account you wish to add an alias to.
Click on 'E-mail addresses'
Click 'Add New E-mail Address'
Enter the e-mail address required and click 'Submit'
Changing the default e-mail address
To change the primary email address of an account follow the above up to STEP 5 then perform the additional steps below
Click 'Change' below the primary e-mail address
Click 'Set as primary e-mail address' next to the e-mail address you wish to set
If you wish to change the user's login to the default e-mail address, tick the box marked 'Synchronize Service User's login'. Click 'Finish'. This completes the change of the default e-mail address.