Can I change my default email address?
Yes, you can edit your default email address at any time. When you change an email address, mail sent to the original address will be returned to the sender (unless you've activated your catch-all mailbox)
To edit an email address:
Visit your Email Control Panel.
Click the "Edit User" link for the user you'd like to edit. (The default email address is the one without a "Delete User" link.)
Email Control Panel - Edit User Link
On the Edit User page, click "Change email".
Email Control Panel - Change Email Link
In the pop-up dialog box, enter the new email address and then click the Save button.
Email Control Panel - Change Email Address Dialog Box
If you've set up POP to check your email, be sure to edit those settings to reflect your new email address.