First, you just validated your address. Second, you just told them that you actually read their spam, that you didn't filter it out. There are a lot of free speech and privacy issues surrounding spam. It's a fact of life. Every now and then I receive an ad that informs me of a product or service I really need.
Advertising is a fact of commercial life.
I am opposed to people abusing their access to me. I think spam should be honest, legal, and that anyone who wants to advertise to me should properly identify themselves. Privacy is another issue. On the one hand, it is easy to say that we should all be honest and identify ourselves. On the other hand, there are situations where a person should be able to be annonymous.