A catch-all mailbox receives email messages sent to inactive addresses under the very same domain. For instance, a message sent to the misspelled suport@domain.com will go to support@domain.com in case the catch-all feature has been activated for the latter. Thus, you can receive email messages from friends or customers who may have sent a message to your email address with a typo or to an obsolete 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 a certain moment you may start receiving spam messages in the catch-all mailbox and the forwarding restriction means that the spam will not be sent to a 3rd-party mailbox.