I don't know enough to have an opinion about whether it's illegal, but even assuming it is, that doesn't mean it's immoral.
Typically, what is ethical is respecting the user wishes. If I say, "Don't contact me for commercial interest" (the checkbox when you post something on Craigslist) and you do so, I would say that doesn't conform to business ethics.
To address your other post, I would assume that you're getting down-voted because you're playing devil's advocate by presenting that argument in a discussion of something that almost all of us would agree is immoral, regardless of legality.