Bounces registration attempts of spam bots and spammers with one time mailer addresses.
Error message: You can define the error message that is displayed if the mail domain is rejected by the plugin. You can use the placeholder "%s" to display the rejected domain name.
Blacklist: You can block subdomains, domains, or complete TLDs. "test.tld" will block mail domains ending with "test.tld", ".tld" will block all domains ending with ".tld"
Whitelist: Same as the Blacklist except that it will allow domains instead of blocking them.
Botscout API key: By aquiring an API key you can increase you daily number of free request (20) to a much larger number. You can get your API key here: http://botscout.com/getkey.htm
The mail domains are checked in the following order: Whitelist, Blacklist, List of known disposable mail services, botscout.com