A catch-all email alias address, receives email messages that are sent to a domain for those email addresses that do not exist. While this feature can be convenient, it can also catch a lot of spam. Additionally, every message received is also counted as a message sent because an alias email address forwards messages to a valid inbox.
Log into the SmarterMail Web Interface and under the menu item, click SETTINGS. On the left menu expand DOMAIN SETTINGS and click ALIASES. You must have at least one alias account to set up the catch all. Click SET CATCH ALL and select the alias account from the dropdown. Finally, SAVE your settings.