How to retrieve user email from [e-mail]

[faisal.qureshi.7121614_1]

Hello friends!
I have my site database where users created their accounts with fb connect system in past, which is stored in 'email' field of my users mysql table, other users who created accounts using my website's own registration form is also stored in email field, but how can i retrieve actual email address of a person who logged in using fb connect system? because i need to make an internal Messaging system for members which is working fine for other users but have no idea how to inform users who has facebook connect accounts because i don't have their actual email addresses stored in my db, which is like in this shape [e-mail]

Any help and suggestion will be appreciated.
Thanks!

[lps]

Maybe a little more google shall answer your question. Here is an example: http://stackoverflow.com/questions/3611682/facebook-graph-api-how-to-get-users-email
Instead of storing [e-mail], I suggest your site to store the email used to register the fb account.