A catch-all email mailbox receives messages sent to non-existent email addresses under the exact same domain. For instance, an email message sent to the misspelled firstname.lastname@example.org will go to email@example.com if the catch-all feature has been enabled for the latter. Thus, you can get email messages from colleagues or clients who may have sent a message to your email address with a spelling error or to an obsolete one, which they may still have, but you have already deleted. Just one single 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 a certain point you may start receiving spam emails in the catch-all mailbox and the forwarding restriction implies that the spam will not be sent to a 3rd-party mailbox.