A catch-all mailbox receives messages sent to non-existent addresses under the same domain. For instance, an email sent to the misspelled firstname.lastname@example.org will go to email@example.com if the catch-all feature has been enabled for the latter. Thus, you can get messages from pals or customers who may have sent a message to your email address with a typographical error or to an out-of-date one, which they may still have, but you have already deleted. Just one mailbox per domain name 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 re-sent to a third-party mailbox.