A catch-all email mailbox receives messages sent to non-existent addresses under the very same domain. For instance, an email sent to the mistyped email@example.com will be delivered to firstname.lastname@example.org if the catch-all feature has been activated for the latter. Thus, you can get email messages from acquaintances or customers who may have sent a message to your email address with a spelling error or to an outdated one, which they may still have, but you have already deleted. Only 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 moment you may begin receiving spam emails in the catch-all mailbox and the forwarding restriction means that the spam will not be delivered to a third-party mailbox.