To turn your catch-all mailbox on or off:
Visit the Email Control Panel, and click "Additional Options."
In the blue "Catch-all Mailbox" box, click "Assign catch-all."
In the pop-up that opens, choose an email address to use as the catch-all.(Note that only active users will appear in the pop-up.)
If you decide you don't want a catch-all, click "I don't want a catch-all mailbox."
On the Additional Options page, click "OK."
Note that if you have Custom Mailbox, you may use a catch-all mailbox, but you must either choose your default email address as the catch-all, or opt to turn it off. If you have Business Mail, you may designate any active email user's email address as the catch-all.