A catch-all functionality that is enabled for a given email mailbox will permit you to receive emails that are sent to email addresses that do not really exist. In other words, if you disable an email address and somebody still sends a message to it, or to any mistyped email address under the same domain, you’ll receive the message in the catch-all mailbox. Using this feature implies that you won’t miss an email for any reason, which could be essential if you run some business, for example. Since you may start receiving spam email messages, you can combine the catch-all option with email filters so as to get only authentic email messages in your inbox. Just one single mailbox per domain can be a catch-all one and email forwarding cannot be enabled for a catch-all mailbox.