check if an email address is in a table through a form with 1 field , built in php smarty

I currently have a folder "ticketadmin" in our website we use as a backoffice that uses Smarty PHP. In it I have a folder "reports". For this project I would like a new folder "/ticketadmin/mail" that shows a form with 1 field = email . When in that field 5 letters are typed, the auto-fill-in (I use already) shows the email addresses that can be found in one table , in one field . When the "Send" button is clicked , it checks the table if that email address is in it. If yes : show a phrase "YES, this email address has subscribed" on green background , if no : show a phrase "NO, this email address has not subscribed" on red background on top of the form . For someone who knows PHP Smarty, this should be a one hour job. The print screen is an example of a screen I already use that goes in the same direction of searching info in the same dbase , returning info at the top of screen.