A catch-all functionality that is enabled for a specific mailbox will permit you to receive emails that are sent to addresses that do not actually exist. To put it differently, if you deactivate an email address and somebody still sends an email message to it, or to any mistyped email address under the very same domain, you’ll get the message in the catch-all mailbox. Using this feature means that you won’t miss an email for any reason whatsoever, which could be vital if you are running a company, for instance. Since you may start receiving spam emails, you can use the catch-all option with email filters so as to get only legitimate email messages in your inbox. Just one mailbox per domain can be a catch-all one and email forwarding cannot be set up for a catch-all mailbox.