Sounds to me like you've jumped in when it would have been a good idea to test the water with your toe first.
Most sweeps are legitimate and above board, including those that want to send you emails. There are however some that are less than perfect and a few that you should just totally avoid. The only way to tell is to be vigilant and suspicious until you gain experience. It's always a good idea to read the rules and privacy policy. Always remember, if a sweep sounds to good to be true, it probably is.
Here's one for $10,000 that I found on another sweep site. I don't believe it's listed here a SA, although I've found similar sweeps listed here.
Entry Form:
Win $100 worth of free samples
Rules:
LIFESCRTIPT ADVANTAGE $10,000 SUMMER SWEEPSTAKES OFFICIAL RULES (?OFFICIAL RULES?)
If you open the entry form, you'll find that their intentions regarding emails fully disclosed. That's commendable, some sites hide this info in the rules.
Open the rules, then scroll down to the 4th paragraph (prize) and read it - no guaranteed winner. Then scroll down to the paragraph that starts (winner selection) and read it. Last, scroll down to the next to last paragraph (arbitration) and read it. I suggest you google "mandatory arbitration clause" for an in depth definition - you loose your right to sue or to initiate or participate in a class action lawsuit. I don't know what you'd sue for in a sweepstakes, so that's probably not an issue. Many (most?) sweepstakes now include these clauses. I've never sued anyone, but I reuse to give up my right to sue. Seems like everyone, even Doctors want you to sign such clauses. I've read many news stories on ABC, CBS, NBC & CNN about the fact that the Justice Dept is looking into these mandatory arbitration clauses with the intent to reign them in or limit their use.
I think many sweepers would avoid this sweep if they read the entry form disclosures and the rules. Unfortunately, many of us don't.