A catch-all functionality that is activated for a given mailbox will allow you to receive emails that are sent to email addresses that do not really exist. Otherwise put, if you delete an email address and someone still sends an email to it, or to any misspelled address under the exact same domain name, you’ll get the message in the catch-all mailbox. Using this feature means that you will no longer miss an email for any reason, which could be essential in case you are running some business, for instance. Since you may begin receiving unsolicited bulk emails, you can use the catch-all option with anti-spam filters in order to get only legitimate email messages in your inbox. Just one mailbox per domain can be a catch-all one and email forwarding cannot be set up for a catch-all mailbox.