Why data changed auto

[prokhaled]

I tried to send message as HTML and I used that headers
$headers .= "Content-Type: text/html; charset=iso-8859-1\n";

the message has been send as html but there is a problem in a message

the problem that this code: <img src="http://vbs.8k.com/banner.gif">
changed auto to this code: <img src="\http://vbs.8k.com/banner.gif">
so the image does not appear !!

I do not add any (\) in code ??

How can I solve this problem ???

Thanks