YA: Contact Form Processing

<?php
/*
    script simplification for:
    http://answers.yahoo.com/question/?qid=20110617205843AAeDwtm
*/

define('BACK_MSG', ' Please hit your browser back button and <a href="Javascript: history.go(-1);">try again</a>.');

/*
*            FUNCTIONS
*/
function requiredField($name,$msg){
    if(strlen($_REQUEST[$name]) === 0){
        die($msg);
    }
}
function checkemail($field) {
    // checks proper syntax
    if( !preg_match( "/^([a-zA-Z0-9])+([a-zA-Z0-9._-])*@([a-zA-Z0-9_-])+([a-zA-Z0-9._-]+)+$/", $field)){
        die("Improper email address detected." . BACK_MSG);
    }
    return $field;
}
function spamcheck($field){
    // eregi is depricated, as well as resource heavy compared to str functions. Each has their place, this is not eregi's place.
    $spamMarkers = Array("to:","cc:","bcc:","\r","\n","%0A");
    $c = count($spamMarkers);
    $lowered = strtolower($field);
    for($i = 0; $i < $c; ++$i){
        if(strpos($lowered,$spamMarkers[$i]) !== false){
            // No need to set $possiblespam, or return 1,  as Script die's
            die("Possible spam attempt detected. If this is not the case, please edit the content of the contact form and try again." . BACK_MSG);
        }
    }
    return $field;
}
function strlencheck($field, $minlength, $whichfieldresponse){
    if (strlen($field) < $minlength){
        die($whichfieldresponse);
    }
}

/*
*            REQUIRED INPUT CHECKS
*/
requiredField('subject',"You did not choose a subject line." . BACK_MSG);
requiredField('emailaddress',"You did not choose a recipient." . BACK_MSG);

/*
*            VARIABLES
*/
$sentPage = 'email_sent.php'; // Page that the user will be sent to on a successfull email send
$notSentPage = 'email_not_sent.php'; // Page that the user will be sent to if there was an error with the sending of the email.
$email = spamcheck(checkemail($_REQUEST['email']));
$message = $_REQUEST['message'];

$subject = Array(
    '1' => "Membership/Burgees",
    '2' => "Submitting content (articles/pictures etc...)",
    '3' => "Voyage planning",
    '4' => "Suggestions",
    '5' => "Other");
$subject = $subject[$_REQUEST['subject']];

$emailaddress = Array(
    '1' => "[email protected]",
    '2' => "[email protected]",
    '3' => "[email protected]");
$emailaddress = $emailaddress[$_REQUEST['emailaddress']];

/*
*            INPUT CHECKING
*/
strlencheck($email, 10, "The email address field is too short." . BACK_MSG);
strlencheck($subject, 1, "You did not choose a subject." . BACK_MSG);
strlencheck($message, 10, "The message field is too short." . BACK_MSG);
strlencheck($emailaddress, 8, "You have not selected a recipient of your message." . BACK_MSG);

/*
*            EMAIL SENDING
*/


// All Checks will stop the script if there is an error. So no need to check for errors when the script will die() on errors.
if(mail($emailaddress,"Subject: {$subject}",$message,"From: {$email}" )){
    // Mail sent successfully
    header("Location: {$sentPage}");
    exit;
}else{
    header("Location: {$notSentPage}");
    exit;
}
?>