Blacklists feature let recipients to include their email addresses in a blacklist in order to block send future emails from app asociated to that blacklist.
Also, the system can include a email address in a auto-blacklist when it detects that email address has permanent errors.
That is, each app can contain a blacklist and an auto-blacklist.
For activating blacklist feature you must use useblacklist=true when creating/editing your app.
For activating auto-blacklist feature you must use useautoblacklist=true when creating/editing your app.