Hello friends please can any one help me how where mail() validation put in this code for short form.

Code here:-

<?php
if (isset($_REQUEST['email']))
//if "email" is filled out, send email
{
//send email
$email = $_REQUEST['email'] ;
$subject = $_REQUEST['subject'] ;
$message = $_REQUEST['message'] ;
mail("info@yoursitesite.com", "$subject",
$message, "From: $email" );
echo "Thank you for using our mail form";
}
else
//if "email" is not filled out, display the form
{
echo "<form method='post' action='inquiry.php'>
Email: <input name='email' type='text' /><br />
Subject: <input name='subject' type='text' /><br />
Message:<br />
<textarea name='message' rows='15' cols='40'>
</textarea><br />
<input type='submit' />
</form>";
}
?>

not clear what do you meant by "how where mail() validation put in this code"

if you meant email validation here is the code:

PHP Code:

if (!eregi("^[_a-z0-9-]+(\.[_a-z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,3})$", $email)){ 
          echo "Error: You have NOT entered the correct email address. "; 
      } 


if you want to validate against email injection, here is the code

PHP Code:

if (ereg( "[\r\n]", $email ) ) { 
echo "error!";
}