Login to Admin Portal with admin account.

Click the Admin drop down menu in upper right and click Exchange.

Double click on the user you would like to edit.

1. Click email address from the menu on the left.
2. Click the + button to add alias address.

Note: From here you can also see the list of alias (SMTP) addresses associated with the user.

1. SMTP should be checked.
2. Type in alias email address and click OK.
3. Optional: Click this box to make the alias the reply address. Note: Your login username will not change.