A catch-all feature that is enabled for a certain mailbox will allow you to receive emails that are sent to addresses that do not actually exist. Otherwise said, if you disable an email address and someone still sends an email message to it, or to any misspelled email address under the exact same domain, you’ll get the email in the catch-all mailbox. Using this functionality means that you won’t miss an email for any reason, which could be crucial in case you are running a business, for example. Since you may begin receiving unsolicited messages, you can use the catch-all feature with anti-spam filters in order to get only legitimate emails in your inbox. Just one single mailbox per domain can be a catch-all one and email forwarding cannot be enabled for a catch-all mailbox.