A catch-all mailbox receives email messages sent to non-existent addresses under the same domain. For instance, an email sent to the misspelled email@example.com will be delivered to firstname.lastname@example.org in case the catch-all feature has been enabled for the latter. Thus, you can receive messages from colleagues or customers 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. Just one single mailbox per domain name can be a catch-all one and email forwarding cannot be activated for such a mailbox. The latter is due to the fact that at some moment you may begin 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.