Hey *MO*,
In order for your emails to be sent in HTML form, rather than plain text, you need to send the content-type through within the header. If you don't specify a content-type, it defaults to plain text.
$headers .= "--$boundary\r\n"."Content-Type: text/html; charset=ISO-8859-1\r\n";
That should allow the user who receives your email to see the link in proper form, and not all the code.
Hope this helps,
-SlickVic78