Junkanoo sits between youy email server and client, acting as a filter for spam messages. It doesn't work in the usual way where you "train" the program according to the type of messages you receive. Instead of that, Junkanoo displays the messages still on your server and allows you to filter them before actually downloading them with your favorite email client.
The program marks messages as spam according to the most typical characteristics of this kind of messages: empty subject lines, links inside the message, strange characters, etc. However, it is you who has to manually mark each message as definitive spam or approve it to enter your inbox. Junkanoo also has support to create white and black lists for allowed and banned sender domains respectively.
Besides filtering spam in your mailbox, the program includes a small editor to send messages from Junkanoo, featuring also a spellchecker.