A catch-all mailbox receives messages sent to nonexistent email addresses under the very same domain name. For example, an email sent to the misspelled firstname.lastname@example.org will be delivered to email@example.com if the catch-all feature has been enabled for the latter. In this way, you can receive messages from mates or customers who may have sent a message to your email address with a typographical error or to an obsolete one, which they may still have, but you have already disabled. 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 a certain point you may begin receiving spam emails in the catch-all mailbox and the forwarding restriction means that the spam will not be redirected to a 3rd-party mailbox.