Here's the big problem. If you make the mistake of clicking on the "Unsubscribe" button in a spam letter, you let the spammer know you actually opened it. Instead of getting unsubscribed, you get more spam than ever!!!
Reporting them to the authorities won't work, either. Spam is rarely sent directly from the spammers' machines. They use bots, computers that they hijack with trojans/backdoors, for their spamming, to avoid getting caught.
I have two suggestions for you: The first is to use MailWasher. It offers a "bounce" feature that allows you to reject the letter and send it right back to the sender. Not only is this a nuisance to the spammer, it also makes it look like your account no longer exists, and the spammers back off. No other anti-spam works like this one.
My other suggestion is to switch to an e-mail provider that offers response challenge. When a sender who is not on your whitelist tries to send you an e-mail, it goes into a "pending" folder and waits. Then the server sends them a request for "verification."
In some cases, you can require them to specify your full name, or even enter a password, but this could be more trouble than it's worth. As is, just asking them to click a "respond" button is enough. Computers are unable to respond to these challenges, so the e-mails they send never make it into your inbox unless you go into the pending folder and whitelist them yourself.