A catch-all email mailbox receives messages sent to non-existent addresses under the very same domain name. For example, an email message sent to the miswritten suport@domain.com will be delivered to support@domain.com in case the catch-all feature has been activated for the latter. In this way, you can receive messages from friends or customers who may have sent a message to your email address with a spelling mistake or to an old one, which they may still have, but you have already disabled. Only one single mailbox per domain can be a catch-all one and email forwarding cannot be activated for such a mailbox. The latter is due to the fact that at a certain point you may start receiving spam emails in the catch-all mailbox and the forwarding limitation means that the spam will not be re-sent to a 3rd-party mailbox.