Fake sendmail - write content to file

sendmail.php

#!/usr/bin/php
<?php
    /**
    * Fake mail sending: log content to file
    *
    * Instructions:
    *     1. Save as /usr/sbin/sendmail
    *     2. Make it executable
    */

    $date = new DateTime();
    $file = '/tmp/fakemail_'.$date->format('d-m-Y_H:i:s').'.log';

    $log = fopen ($file,'a+');

    fwrite($log,file_get_contents("php://stdin"));
    fclose($log);
?>