A catch-all mailbox receives email messages sent to non-existent email addresses under the very same domain. For example, an email message sent to the mistyped 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 pals or clients who may have sent a message to your email address with a typo or to an obsolete one, which they may still have, but you have already deactivated. Just one single 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 moment you may begin receiving spam messages in the catch-all mailbox and the forwarding limitation implies that the spam will not be received in a 3rd-party mailbox.