unsolicited and harassing emails

For years now I have been receiving emails from various email addresses, all pertaining to Viagra and the Canadian  pharmacy. The latest batch all begin with info the a number and no matter how many rules I create they always get through. All I need to know now is how I can sue this company and put a stop to them for good. Their excuse in the past has been they have no control over third parties, but I disagree. I do not believe for one minute that anyone would send out thousands of emails without payment or reward. So lets sue this company out of business.