Data matching | Database | Newsletter subscription | Form

Hello guys,

Before I waste more hours to find a solution maybe you guys can help me out with following situation:

I have a contactform on a landingpage. When a person fills out the form I want to check if the email already exists in our database.

If the email is not known there should be a redirect to another "please suscribe to .... before downloading..."- page. Is there any solution like a script or something that I can implement.

I know that there is the possibility of recognition with munchkin or cookies but this shouldnt be the solution for this case.