Hey HN, I'm a longtime reader and this is my first Show HN (exciting!) It's a collaboration between me and two friends, and we're building this upon another app we made called EmailYak, an API to receive email. We're trying something new and releasing the documentation to an app while we're still building it.<p>We'd love feedback. Do you belong to any of these categories?<p>1) You've built an app with two distinct groups of users (say, people with cars and those looking for a ride) and they were able to communicate with each other. Did you expose personal email addresses? Did you send notification emails that people could reply to directly in their inbox? Or were they only able to read and reply to messages on your site?<p>2) You built an app where you wished users could message each other but didn't add that feature. What stopped you? Did you try to parse incoming email? What tools or APIs did you try out?<p>If you note which group(s) above you belong to in your comment that'd be great :)<p>Thanks so much for the help!