php - Why is my e-mail still being picked up as spam? Using mail() function

Question

I've been getting very annoyed at this as no matter what it seems spam filters are still calling my websites auto responder as spam. I've set all my headers correctly and this is what I have so far!

$headers = "From: Name<name@website.com>
"
        ."Return-Path: Name<name@website.com>
"
        ."Reply-To: Name<name@website.com>
"
        ."Message-ID: <". time() .rand(1,1000). "@".$_SERVER['SERVER_NAME'].">
"
        ."X-Mailer: PHP v".phpversion()."
"
        ."MIME-Version: 1.0
"
        ."Content-Type: text/plain; charset=iso-8859-1
";

        @mail($_POST['email'], "Subject", "Message", $headers);

Please help me on this one! :)

This is being sent from my shared hosting providers servers.

would it help if I added the 5th parameter as below?

"-f email@website.com"

Answer 1

Have you read this?

So You'd Like to Send Some Email (Through Code)

In a nutshell:

1. Make sure the computer sending the email has a Reverse PTR record
2. Configure DomainKeys Identified Mail in your DNS and code
3. Set up a SenderID record in your DNS