A catch-all email mailbox receives emails sent to nonexistent email addresses under the very same domain name. For example, an email message sent to the mistyped email@example.com will go to firstname.lastname@example.org in case the catch-all feature has been enabled for the latter. Thus, you can get emails from friends or clients who may have sent a message to your email address with a typographical error or to an old one, which they may still have, but you have already disabled. Only one single 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 emails in the catch-all mailbox and the forwarding limitation means that the spam will not be delivered to a 3rd-party mailbox.