BoxTrapper (cPanel Tool) is described as 'BoxTrapper is a tool that filters spam from your inbox through a process called challenge-response verification. When an account that has BoxTrapper enabled receives an email, it automatically sends a customizable verification email in response' and is a Anti-Spam tool in the security & privacy category. There are three alternatives to BoxTrapper (cPanel Tool) for a variety of platforms, including Linux, Mac, Windows, Chrome OS and BSD apps. The best BoxTrapper (cPanel Tool) alternative is SpamAssassin, which is both free and Open Source. Other great apps like BoxTrapper (cPanel Tool) are Anti-Spam SMTP Proxy Server and SmartInbox.
No option to bounce (reject) incoming messages