There is this thread at SEO Chat named Email Addresses Count as Backlinks which discusses someone's case of finding email addresses being counted as backlinks. The member did not provide any example, but the topic is different.
Members that are skeptical of such a theory state that the @ symbol is being turned into a ? by Google. Then Google is doing a match on the part after the ?, which happens to be the domain name.
Anyway, I guess this theory can be tested. Just put a new domain, make sure no one links to it, and then link to an email with the domain name of the new domain. Only problem with this is that many newly registered domain names are picked up by search engines because someone is out there linking to them for one reason or an other.