How can I know the emails of people visiting a sit

Is there any way in PHP to collect the email address of a visitor? I wish to use it for their user id.

Thanks

Elizabeth

I do not believe that this is possible and I pray that it isn't.
Ask visitors for their email address, otherwise this would be considered a gross invasion of privacy. A growing number of websites have a Privacy Policy statement that they will not collect personally identifying information without consent. See www.TRUSTe.com for guidelines.
Doug

i am searching a fashion girl who lives in australia.she emmigratedfrom bosniain 1994.
please send her email if it's possible.
my thanks in advance