While you want to make sure you're requesting freebies from a reliable website, you should also make sure you're finding your freebies on a reliable freebie website. The company is breaking Spam laws by not having a functioning "unsubscribe" button.
Jessy, the site you mentioned, seems to only list sweepstakes and not actual free stuff. But they keep on flood me with email. I've filed complaints and later asked the BBB if the company had any complaints filed against them. Vonbeau is my favorite website. Well, this came up because they mailed my daughter a Vibrator.
Many times when you request a freebie, the company will want your phone number and email address. Question 13 of Poor 2.