A catch-all email mailbox receives email messages sent to invalid addresses under the exact same domain name. For instance, a message 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. Thus, you can get email messages from mates or clients who may have sent a message to your email address with a typographical error or to an old one, which they may still have, but you have already deactivated. 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 start receiving spam messages in the catch-all mailbox and the forwarding restriction implies that the spam will not be delivered to a 3rd-party mailbox.