A catch-all mailbox receives email messages sent to inactive addresses under the very same domain. For instance, a message sent to the misspelled firstname.lastname@example.org will be delivered to email@example.com if the catch-all feature has been activated for the latter. In this way, you can receive emails from partners or clients who may have sent a message to your email address with a spelling mistake or to an obsolete one, which they may still have, but you have already deactivated. Only one mailbox per domain name 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 moment you may start receiving spam emails in the catch-all mailbox and the forwarding limitation implies that the spam will not be re-sent to a 3rd-party mailbox.