A catch-all functionality that is enabled for a given mailbox will permit you to receive email messages that are sent to email addresses that do not really exist. To state it differently, if you delete an email address and somebody still sends a message to it, or to any mistyped address under the same domain name, you will get the email in the catch-all mailbox. Using this functionality means that you won’t miss an email for any reason whatsoever, which could be essential if you run a company, for instance. Since you may begin receiving spam messages, you can combine the catch-all option with anti-spam filters in order to get only authentic messages in your inbox. Just one single mailbox per domain can be a catch-all one and email forwarding cannot be set up for a catch-all mailbox.