A catch-all email mailbox receives emails sent to non-existent addresses under the same domain. For instance, 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 receive email messages from acquaintances or customers who may have sent a message to your email address with a typo or to an old one, which they may still have, but you have already deleted. Only one 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 a certain moment you may begin receiving spam messages in the catch-all mailbox and the forwarding restriction implies that the spam will not be sent to a third-party mailbox.