A catch-all email mailbox receives emails sent to invalid addresses under the exact same domain name. For example, an email sent to the mistyped suport@domain.com will be delivered to support@domain.com if the catch-all feature has been enabled for the latter. In this way, you can get emails 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 deleted. Only one single mailbox per domain can be a catch-all one and email forwarding cannot be activated for such a mailbox. This is so because of the fact that at some point you may begin receiving spam email messages in the catch-all mailbox and the forwarding restriction means that the spam will not be redirected to a third-party mailbox.