The E-mail address Pick-All will "pick up" any email that is sent to an invalid or non-existent address from your domain. To enable the features in your account, enter the user of your cPanel in the email address field. You can set up an email account that will receive invalid messages and an error message.
There are two possibilities for this feature. The default (second) option is to route to a valid email address, which must be filled in the Forward to email address: field. The other option (first) is to return the message to the owner with the custom subject field.