A catch-all email mailbox receives messages sent to invalid addresses under the very same domain. For example, an email message sent to the misspelled 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 email messages from partners or clients who may have sent a message to your email address with a spelling mistake or to an old one, which they may still have, but you have already deleted. Just one mailbox per domain name can be a catch-all one and email forwarding cannot be enabled for such a mailbox. This is so because of the fact that at some moment you may begin receiving spam email messages in the catch-all mailbox and the forwarding limitation means that the spam will not be re-sent to a 3rd-party mailbox.