Messages form

forms.php
<?php
session_start();

echo $er;

echo "
     <form name='form1' method='post' action='mail.php'>
              <input name='session_id' type='hidden' value=".session_id().">
         Name:<br>
              <input type='text' name='name' id='textfield' maxlength='15'>
              <br>
              <br>
         Messages text:<br>
              <textarea name='message_text' cols='60' rows='5'></textarea><br><br>
              <input type='submit' name='button' id='button' value='Send'>
        </form>
    ";
?>


mail.php
<?php
session_start();
if($_POST['session_id'] != session_id() )
{
    exit("Messages Form to use only on a site".$_SERVER['HTTP_HOST'].".");
}
else
{

    $message_text = htmlspecialchars(trim($_POST['message_text']));
    $name = htmlspecialchars(trim($_POST['name']));


    $len = 450; // limit text
    if(strlen($message_text) > $len)
    {
        exit("Error. Messages limit  ".$len. " text. ");
    }


    $to = "[email protected]";
    $subject="Messages for".$name;


    $subject = convert_cyr_string($subject,'w','k');

    // это само письмо
    $message ="<html>
               <head></head>
               <body>
               Mesenger Send  - <font color='red'>".date("d.m.Y H:i:s"). "</font><br>
              <h3>Text Messages:</h3>". $message_text."
               </body>
               </html>
               ";

    $message = convert_cyr_string($message,'w','k');

    $headers = "  headlines send ";

    $headers .= "From: server <name company >\r\n\r\n";
    if(mail($to,$subject,$message,$headers))
    {
      echo "Send Messages Successful .";
    }
    else
    {
      echo "Error. Messages not Send.";
    }
}
?>