A catch-all functionality that is activated for a specific e-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 a message to it, or to any mistyped address under the same domain, you will receive the message in the catch-all mailbox. Using this functionality means that you will no longer miss an email for any reason whatsoever, which could be essential if you run a business, for example. Since you may start receiving unsolicited messages, you can combine the catch-all functionality with anti-spam filtering software so as to get only legitimate messages in your inbox. Just one single mailbox per domain can be a catch-all one and email forwarding cannot be set up for a catch-all mailbox.