A catch-all mailbox receives email messages sent to invalid email addresses under the exact same domain. For example, a message sent to the misspelled 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you can receive emails from mates or customers who may have sent a message to your email address with a typo or to an outdated one, which they may still have, but you have already disabled. Only one mailbox per domain can be a catch-all one and email forwarding cannot be activated for such a mailbox. This is due to the fact that at a certain point you may begin receiving spam email messages in the catch-all mailbox and the forwarding limitation implies that the spam will not be received in a 3rd-party mailbox.