Comment by tart-lemonade

The only real market (that I can see) are shady data aggregators. Governments just file subpoenas, and abusive megacorps can file lawsuits (all the anti-SLAPP statues in the world can't prevent your Google account from being unmasked and having to pay for a lawyer). There is a limited market in the form of internet addicts who want to harass people for kicks (since finding an email gives them another route to do that with), but it's a small one. These people also tend to be entitled pricks, so they're not a very good customer base to have.