A catch-all mailbox receives email messages sent to invalid addresses under the very same domain name. For example, 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 email messages from acquaintances or customers who may have sent a message to your email address with a typo or to an old one, which they may still have, but you have already disabled. Only one single 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 some moment you may begin receiving spam messages in the catch-all mailbox and the forwarding limitation implies that the spam will not be redirected to a third-party mailbox.