A catch-all email mailbox receives emails sent to invalid email addresses under the exact same domain name. For instance, a message sent to the miswritten email@example.com will go to firstname.lastname@example.org in case the catch-all feature has been activated for the latter. In this way, you can get email messages from friends or customers who may have sent a message to your email address with a spelling error or to an outdated one, which they may still have, but you have already disabled. Just 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 point you may start receiving spam emails in the catch-all mailbox and the forwarding restriction implies that the spam will not be re-sent to a third-party mailbox.