How to search the user based on e-mail id from webdynpro java

Hi

I have one requirement for find the provided e-mail id is valid id or not. I need to build one custom webdynpro application. that application should accept the e-mail id and it should check against Portal UME whether that e-mail id exist or not if not i should indicate that id -not valid e-mail id.

Please let me know how implement this using UME API. Provide some sample code for it.

Thanks