Email Action In a Web Site

Guys, I have an html page which at the bottom we will have a "contact me" button, this button needs to call out a modal form with 3 textbox fields and then send the email to an account and close the "modal form" but before sending the email we need to make sure we can validate the three existing fields First Name (not empty) Email (not empty and valid email format) CheckBox (I agree with terms is checked) (if not the send email button must be disabled) this all cannot use code behind (meaning aspx pages or php) it MUST use only functions from the html page thru scripts. The smtp server will be used is local, so as you know we need the html page generates the email file on wwwroot\email\drop (hope you know what I mean by that) We are NOT looking for basic stuffs like (using the client email in order to send the email) taking the user out of the page and calling the local email client with filled fields (THIS IS NOT WHAT WE NEED) please before you send you bid make sure you have a clean understand that it's not a big deal and it must be made extremely fast.