A catch-all mailbox receives email messages sent to non-existent addresses under the same domain. For instance, a message sent to the misspelled suport@domain.com will be delivered to support@domain.com in case the catch-all feature has been enabled for the latter. Thus, you can get email messages from mates or clients who may have sent a message to your email address with a typographical error or to an obsolete 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 enabled for such a mailbox. The latter is due to the fact that at some point you may start receiving spam messages in the catch-all mailbox and the forwarding limitation implies that the spam will not be delivered to a third-party mailbox.