I just took a look at email-lists.com. They're definitely a legit company. They have their company address listed on their website. Their address is in Florida. I guarantee you, if it were illegal to purchase anything from them, the U.S. Government would have shut them down.
I believe that mass mailing campaigns are a thing of the past whereas you're better off advertising on twitter, facebook, or other social media. However, I still hear from other sources that mass e-mail campaings still generate a lot of revenue. They're cheap, so you might as well use it. Best of luck.
