It's illegal to sell user data without explicit consent in a lot of countries. It should also be illegal in the US tho due to the Fair Information Practices.
What is defined as explicit consent? Most terms of service and EULAs on websites and software do explicitly give the company the right to sell your data.
Also aren't the FTC's Fair Information Practices just recommendations with no consequences for violating?
Probably "We are going to disclose your data to party X. Do you consent this?". Saying that you are going to share user information with undisclosed 3rd parties seems like a bit too broad.
In the UK, even if you've managed to buy emails it's of no use, you aren't allowed to contact people unless you've had a business relationship for a related product in the last 12 months.
Judges range in how they feel about these complaints, generally you won't be able to claim just for the time they've wasted, you'll have to justify why you have suffered damages. Extreme cases are different, if they're truly wasting huge amounts of your time, but the occasional email is unlikely to be enough for wasted time.
Alternatively, you can get the ICO to tell them off even if you haven't suffered any damages, but that's not always easy…
