A catch-all mailbox receives emails sent to non-existent email addresses under the exact same domain. For instance, a message sent to the mistyped firstname.lastname@example.org will be delivered to email@example.com in case the catch-all feature has been activated for the latter. In this way, you can get messages from colleagues or customers who may have sent a message to your email address with a typo or to an obsolete one, which they may still have, but you have already deactivated. Only one single 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 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 third-party mailbox.