A catch-all functionality that is activated for a specific mailbox will permit you to receive emails that are sent to email addresses that do not really exist. Otherwise said, if you delete an email address and somebody still sends an email message to it, or to any mistyped address under the same domain, you will get the email in the catch-all mailbox. Using this feature implies that you will no longer miss an email for any reason whatsoever, which could be essential if you are running some business, for instance. Since you may begin receiving unsolicited emails, you can combine the catch-all option with anti-spam filters so as to receive only authentic emails in your inbox. Only one mailbox per domain can be a catch-all one and email forwarding cannot be activated for a catch-all mailbox.