A catch-all mailbox receives email messages sent to nonexistent addresses under the same domain. For example, a message sent to the mistyped suport@domain.com will go to support@domain.com if the catch-all feature has been enabled for the latter. Thus, you can receive messages from buddies or clients who may have sent a message to your email address with a typographical error or to an out-of-date one, which they may still have, but you have already disabled. Only one mailbox per domain name can be a catch-all one and email forwarding cannot be enabled for such a mailbox. This is due to 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 re-sent to a 3rd-party mailbox.