在ASP.NET身份中获取使用Microsoft帐户进行身份验证的用户的电子邮件

I'm using the ASP.NET Identity stuff that came with the new MVC 5 templates in VS2013. I've configured external login providers so people can sign up using Google, Facebook, or Microsoft. However, I would still like to get peoples' e-mail address (e.g. for notifications, updates, etc.).I'm using the ASP.NET Identity stuff that came