Contact Form 7 can manage multiple contact forms, plus you can customize the form and the mail contents flexibly with simple markup. The form supports Ajax-powered submitting, CAPTCHA, Akismet spam filtering and so on.
This plug in helps you to create communication between the visitor and it also can increase your website Business.
If you are applying for Adsense Contact Form 7 is very impotent for your website otherwise your website can be rejected from Adsense Approval.