A catch-all email mailbox receives messages sent to nonexistent addresses under the exact same domain. For example, an email sent to the misspelled firstname.lastname@example.org will go to email@example.com if the catch-all feature has been activated for the latter. In this way, you can get messages from colleagues or clients who may have sent a message to your email address with a spelling error or to an outdated one, which they may still have, but you have already deleted. Only one single mailbox per domain name can be a catch-all one and email forwarding cannot be set up for such a mailbox. This is due to the fact that at some moment you may start receiving spam messages in the catch-all mailbox and the forwarding limitation implies that the spam will not be redirected to a 3rd-party mailbox.