A catch-all mailbox receives emails sent to inactive email addresses under the same domain. For instance, an email message sent to the misspelled firstname.lastname@example.org will be delivered to email@example.com in case the catch-all feature has been enabled for the latter. In this way, you can receive email messages from pals or customers who may have sent a message to your email address with a spelling mistake or to an out-of-date one, which they may still have, but you have already deactivated. Only one single mailbox per domain can be a catch-all one and email forwarding cannot be enabled for such a mailbox. This is so because of the fact that at some moment you may start receiving spam email messages in the catch-all mailbox and the forwarding restriction implies that the spam will not be sent to a third-party mailbox.