You can send private messages to any member by clicking on the "contact" button on the top row of any post they've made

You can also click on the person's name wherever you see it, then scroll down the page you find yourself on, and you'll see whatever contact information they've opted to include. You will also see a "private message" link, through which you can send them a message without revealing your email at any time.

Since the messages are fully contained in the community, they can reply to it without revealing their email, too.