It's more than just a blocker for unwanted mail. SpamSit lets you scan pages that send you spam. As if it were a virtual sit-in, you can connect to the website that sends you spam and stay connected, and if you manage to get enough people doing that, you can block its server.
SpamSit focuses on web domains because this is where spammers are financed; without income for them, there's no more spam.
You can also get rid of scams from mails that pretend to be reputable institutions in order to get your bank account information, by generating automatic responses with false data. If these people receive lots of this type of response, it becomes harder for them to get real information from the people who've fallen into their traps.
Trial version works for 14 days.