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. In other words, if you deactivate an email address and someone still sends a message to it, or to any miswritten address under the exact same domain, you will receive the message in the catch-all mailbox. Using this feature implies that you will no longer miss an email for any reason, which could be vital in case you are running some company, for instance. Since you may start receiving spam, you can combine the catch-all feature with anti-spam filters in order to get only legitimate messages in your inbox. Just one single mailbox per domain can be a catch-all one and email forwarding cannot be activated for a catch-all mailbox.
