try this

<?php
if(!isset($_POST['submit']))
{
    //This page should not be accessed directly. Need to submit the form.
    echo "error; you need to submit the form!";
    //header("location:index.html");//you can change later
}

//echo '<pre>'.print_r($_POST,1); exit; //comment this line to continue
$name = $_POST['name'];//remember.. name not using capitalize
$email_address = $_POST['email_address'];
$phone = $_POST['phone'];
$comments = $_POST['comments'];
 // better using read able name.. above is fine.. but using capitalize name whould be hard to type, I understand that so I should LC all of it. but also make suret the values match the form names right?
//Validate first
if(empty($name)||empty($email_address))  //$visitor_EMAIL_ADDRESS is not valid.. but you should  check this should type $EMAIL_ADDRESS
{
    echo "Name and email are mandatory!";
    //the email will not be empty... but you need to check if the email is valid
    //   http://stackoverflow.com/questions/12026842/how-to-validate-an-email-address-in-php
    exit;
}

$email_from = 'karljames@verizon.net';'gundambison@gmail.com';'kjames1973@gmail.com';//<== Put your email address here
$email_subject = "New Form submission";
$email_body = "You have received a new message from the user $name.\n".
    "email address: $visitor_email_address\n".
    "Here is the COMMENTS:\n $comments".

$to = "karljames@verizon.net";//<== Put your email address here
$headers = "From: $email_from \r\n";

//Send the email!
mail($to,$email_subject,$email_body,$headers);
echo "<br/>sending email";
//this email function not always work as we wanted

    /*
    for first.. hope this mail work
    if not.. search how to using SMTP or other ways to email...
    */
//done. redirect to thank-you page.
die("success");
//header('Location: thank-you.html'); //try not using header...
    //using js goto
    //    http://stackoverflow.com/questions/9803978/javascript-method-to-navigate-to-other-url



?>