A catch-all email mailbox receives email messages sent to inactive email addresses under the very same domain name. For instance, an email sent to the misspelled firstname.lastname@example.org will be delivered to email@example.com if the catch-all feature has been enabled for the latter. In this way, you can receive email messages from friends 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 disabled. Only one single mailbox per domain 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 moment you may start receiving spam email messages in the catch-all mailbox and the forwarding limitation means that the spam will not be received in a 3rd-party mailbox.