A catch-all functionality that is activated for a particular mailbox will allow you to receive email messages that are sent to addresses that do not actually exist. To put it differently, if you disable an email address and somebody still sends an email message to it, or to any miswritten address under the same domain name, you’ll get the email in the catch-all mailbox. Using this feature means that you won’t miss an email for any reason whatsoever, which could be crucial if you are running some business, for example. Since you may start receiving spam messages, you can use the catch-all option with email filters in order to receive only legitimate email messages in your inbox. Only one single mailbox per domain name can be a catch-all one and email forwarding cannot be activated for a catch-all mailbox.