A catch-all email mailbox receives messages sent to nonexistent addresses under the very same domain name. For instance, a message sent to the mistyped 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you can receive messages from friends or clients who may have sent a message to your email address with a typo or to an outdated one, which they may still have, but you have already deactivated. Only one mailbox per domain can be a catch-all one and email forwarding cannot be set up for such a mailbox. This is so because of the fact that at a certain point you may start receiving spam email messages in the catch-all mailbox and the forwarding restriction implies that the spam will not be received in a third-party mailbox.