A catch-all email mailbox receives messages sent to invalid addresses under the same domain. For example, an email sent to the miswritten suport@domain.com will be delivered to support@domain.com in case the catch-all feature has been activated for the latter. Thus, you can get email messages from acquaintances or clients who may have sent a message to your email address with a typo or to an out-of-date one, which they may still have, but you have already deleted. Just one mailbox per domain can be a catch-all one and email forwarding cannot be activated for such a mailbox. This is due to the fact that at a certain point you may begin receiving spam emails in the catch-all mailbox and the forwarding restriction implies that the spam will not be redirected to a 3rd-party mailbox.