But it's to the users of the service to share their dialzoo url including their email. Like http://dialzoo/your@email.com
Our assumption is that people would use email that are consider public info already, and share that.
Perhaps this is more relevant for public profiles such as - business website - public social profiles like linkedin. - facebook - google +
Because in the latter case (which is what I think the service is), you could make the users register their email address (using a verification email to ensure they do not register someone else email without their consent) in your service and then have a map from a random hash to the email, allowing you to provide urls looking like dialzoo.com/nzef1824Ldaw68873 rather than forcing user to publish their email in clear. Or even require a username and use that for the URL.
http://www.developer.it/post/gravatars-why-publishing-your-e... http://archive.hack.lu/2013/dbongard_hacklu_2013.pdf