I've researched this intensely. Here, at Stack Overflow, I've figured out that one needs to use an -f parameter with the php mail() function, if one wants undeliverable mail to bounce back. Following is my script (as it stands now):
//Send Confirmation email. Following are the variables for the email
// mail function best practices: http://collaborate.extension.org/wiki/Best_Practices_Using_the_PHP_mail_Function
$sendto = $email; // this is the email address collected from the foreach routine.
$e_subject = stripslashes($subject); // Subject
//$message = "<html>" . stripslashes($body) . "</html>";
$message = "
<html>
<body>
<p>Hello " . stripslashes($fName) . ":</p>
<div>" . stripslashes($body) . "</div>
</body>
</html>
";
// Always set content-type when sending HTML email
$header = "MIME-Version: 1.0" . "\r\n";
$header .= 'Content-type: text/html; charset=iso-8859-1' . "\r\n";;
// extract user domain so you can set up X-Mailer
$u_domain=substr(strrchr($user_email, '@'), 1);
$dom_array = explode(".",$u_domain);
$user_domain = $dom_array[0];
$header .= "X-Mailer: ". $user_domain ."\r\n";
$header .= "X-Sender-IP: {$_SERVER['REMOTE_ADDR']}\r\n";
$header .= "X-Originating-IP: [".getenv("REMOTE_ADDR")."]\r\n";
$header .= "From: " . $user_email . "\r\n";
$header .= "Sender: ". $user_email . "\r\n";
// The "envelope sender" is the address listed in the "Return-Path:" header - and controls where the email is sent to in the event that a recipient address bounces. http://collaborate.extension.org/wiki/Best_Practices_Using_the_PHP_mail_Function
$header .= "Return-Path:" . $user_email . "\r\n";
$header .= "Reply-To:" . $user_email . "\r\n";
$bounceTo = "-f". $user_email;
// Collect variables from above and insert into the mail() function.
mail($sendto, $e_subject, $message, $header,$bounceTo);
You'll notice a lot of commenting - I'm just trying to figure this out. My mail() sends wonderfully. The mail is coming into my inbox with formatting as it should be. But... the $bounceTo variable ("-f" . $user_email) is not working. I've intentionally mailed to 3 known inactive addresses, and I'm not getting any bounce backs.
All the header settings in the above code are in place because I've learned that these may affect bounce backs. I'm totally willing to get rid of un-necessary headers and add what is necessary. But... at this point the script seems to be a mess -which is not producing bounce backs.
Any suggestions are welcome.
Thanks Much:
Pavilion