A catch-all mailbox receives emails sent to inactive email addresses under the same domain name. For example, an email message sent to the misspelled firstname.lastname@example.org will go to email@example.com in case the catch-all feature has been enabled for the latter. Thus, you can get messages from partners or customers who may have sent a message to your email address with a spelling error or to an out-of-date one, which they may still have, but you have already deactivated. Only one single mailbox per domain 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 point you may begin receiving spam email messages in the catch-all mailbox and the forwarding limitation implies that the spam will not be re-sent to a third-party mailbox.