You don't need to find a script. You can write this in 3 seconds.
Your form should look like this:
<form action="page2.php" method=post>
Name: <input type=text name="first_name"><br>
City: <input type=text name="city">
<input type=hidden name="destination_email_address" value="43">
<input type=submit value="Send Us Mail">
</form>
So, as you can see from the form, you are embedding an encrypted email address. It's "43". So in the PHP script, you need to decrypt that like this:
<?php
$email = $_POST['destination_email_address'];
if ($email==1) { $to_email = "bob@smith.com"; }
if ($email==2) { $to_email = "sally@smuthers.com"; }
if ($email==3) { $to_email = "jean@aol.com"; }
if ($email==43) { $to_email = "steve@msn.com"; }
// Then just execute the mail command to send mail to the decrypted
// email address which is in the variable $to_email
?>
This is far more secure than MD5 or any other encryption that you can find. Why? Because "2" simply cannot be reversed to figure out that the recipient was
sally@smuthers.com.