Will this code protect me from most form mail injections?

I add this code to my feedback.php, it's copied from a website ..

[natural number]

Do you think this enough to properly secure a form ..?

<?php
// First, make sure the form was posted from a browser.
// For basic web-forms, we don't care about anything
// other than requests from a browser:
if(!isset($_SERVER['HTTP_USER_AGENT'])){
die("Forbidden - You are not authorized to view this page");
exit;
}

// Make sure the form was indeed POST'ed:
// (requires your html form to use: action="post")
if(!$_SERVER['REQUEST_METHOD'] == "POST"){
die("Forbidden - You are not authorized to view this page");
exit;
}

// Host names from where the form is authorized
// to be posted from:
$authHosts = array("domain.com", "domain2.com", "domain3.com");

// Where have we been posted from?
$fromArray = parse_url(strtolower($_SERVER['HTTP_REFERER']));

// Test to see if the $fromArray used www to get here.
$wwwUsed = strpos($fromArray['host'], "www.");

// Make sure the form was posted from an approved host name.
if(!in_array(($wwwUsed === false? $fromArray['host'] : substr(stristr($fromArray['host'], '.'), 1)), $authHosts)){
logBadRequest();
header("HTTP/1.0 403 Forbidden");
exit;
}

// Attempt to defend against header injections:
$badStrings = array("Content-Type:",
"MIME-Version:",
"Content-Transfer-Encoding:",
"bcc:",
"cc:");

// Loop through each POST'ed value and test if it contains
// one of the $badStrings:
foreach($_POST as $k => $v){
foreach($badStrings as $v2){
if(strpos($v, $v2)!== false){
logBadRequest();
header("HTTP/1.0 403 Forbidden");
exit;
}
}
}

// Made it past spammer test, free up some memory
// and continue rest of script:
unset($k, $v, $v2, $badStrings, $authHosts, $fromArray, $wwwUsed);

?>

[eelixduppy]

Hello,

Related thread [webmasterworld.com]. This thread outlines some very useful techniques.

Good luck!