A catch-all email mailbox receives messages sent to inactive addresses under the same domain. For instance, a message sent to the misspelled suport@domain.com will be delivered to support@domain.com in case the catch-all feature has been enabled for the latter. Thus, you can get messages from pals or clients who may have sent a message to your email address with a typo or to an out-of-date one, which they may still have, but you have already disabled. Just one single mailbox per domain can be a catch-all one and email forwarding cannot be set up for such a mailbox. This is due to the fact that at some point you may start receiving spam emails in the catch-all mailbox and the forwarding restriction implies that the spam will not be delivered to a 3rd-party mailbox.