A catch-all mailbox receives messages sent to inactive email addresses under the very same domain name. For instance, an email message sent to the mistyped suport@domain.com will be delivered to support@domain.com in case the catch-all feature has been enabled for the latter. In this way, you can get emails from partners or clients who may have sent a message to your email address with a spelling error or to an old one, which they may still have, but you have already deleted. Just one single mailbox per domain can be a catch-all one and email forwarding cannot be enabled for such a mailbox. This is due to the fact that at a certain point you may begin receiving spam email messages in the catch-all mailbox and the forwarding restriction means that the spam will not be sent to a third-party mailbox.