mailing problem

[deldadeh]

Hi
i have changed the message.lang.php file some like that sent mails would be changed.
but after i test it , the recived mail doesn't chenge the HTML codes

i recive a mail like this

<div style="PADDING-RIGHT: 0px; PADDING-LEFT: 0px; PADDING-BOTTOM: 0px; MARGIN: 0px; PADDING-TOP: 0px">
<div style="PADDING-RIGHT: 9px; PADDING-LEFT: 9px; FONT-SIZE: 12px; PADDING-BOTTOM: 0px; MARGIN: 0px auto; WIDTH: 100 PADDING-TOP: 0px; FONT-FAMILY: tahoma; TEXT-ALIGN: right">
<div style="BORDER-RIGHT: #9d9d9d 1px solid; BORDER-TOP: #9d9d9d 1px solid; BORDER-LEFT: #9d9d9d 1px solid; BORDER-BOTTOM: #9d9d9d 1px solid; BACKGROUND-COLOR: #b9dcf0">
       <div style="font-size: 11px; line-height: 30px; text-align: center; border-top: 1px solid #9d9d9d; border-bottom: 1px solid #9d9d9d; padding-right: 5px; background: #efedd7">
وب کده </div>
<div style="color: #444444; direction: rtl; border: 1px solid #9d9d9d; margin: 5px; padding: 10px; background: #f9f9f9">


<font face="Tahoma" style="font-size: 9pt">
<p dir="rtl"><p>dear deldadeh<br>
<br>
You have received a new private message on forum from . To view this message, you can follow this link:

And So on ....

what should i do?
what should i change?