A catch-all feature that is enabled for a given mailbox will permit you to receive email messages that are sent to email addresses that do not actually exist. Otherwise said, if you disable an email address and somebody still sends an email message to it, or to any misspelled address under the exact same domain name, you will get the email in the catch-all mailbox. Using this feature implies that you won’t miss an email for any reason, which could be essential if you are running some business, for instance. Since you may start receiving junk emails, you can use the catch-all functionality with anti-spam filters so as to get only legitimate messages in your inbox. Just one single mailbox per domain name can be a catch-all one and email forwarding cannot be set up for a catch-all mailbox.