Dealing with privacy settings and such

So, for this new site I’m working on (similar to craigslist but specifically for textbooks):

Wondering what to do about privacy settings - should I be showing the user’s email for contact purposes? What if they put up their phone number? Is that fair game to display on the site as well?

Would be nice to have a mail server like craigslist’s where the emails are automatically redirected (i.e., sale-123456@… -> my_email@gmail.com) - but have to make do with what I have.