A catch-all mailbox receives emails sent to nonexistent addresses under the exact same domain name. For instance, a message sent to the misspelled firstname.lastname@example.org will go to email@example.com if the catch-all feature has been enabled for the latter. In this way, you can get emails from mates or clients who may have sent a message to your email address with a typographical error or to an outdated one, which they may still have, but you have already deleted. Only one single mailbox per domain can be a catch-all one and email forwarding cannot be enabled for such a mailbox. This is due to the fact that at some moment you may start receiving spam emails in the catch-all mailbox and the forwarding limitation implies that the spam will not be re-sent to a third-party mailbox.