A catch-all mailbox receives emails sent to inactive email addresses under the same domain name. For example, a message sent to the miswritten suport@domain.com will go to support@domain.com in case the catch-all feature has been activated for the latter. In this way, you can receive messages from mates or customers who may have sent a message to your email address with a spelling mistake or to an out-of-date one, which they may still have, but you have already deactivated. Just one mailbox per domain can be a catch-all one and email forwarding cannot be enabled for such a mailbox. The latter is due to the fact that at some moment you may start receiving spam email messages in the catch-all mailbox and the forwarding restriction implies that the spam will not be re-sent to a 3rd-party mailbox.