I'll be blunt - there's quite a few problems here. I'll go over what I see in a glance -
1. You mix PHP4 syntax with PHP5 syntax - using 'var' for properties (which is PHP4 - instead of PHP5 visibility keywords) but __construct() (which is PHP5). I suggest stick with one, preferably PHP5 since it has been out for over 6 years now.
2. You don't need to assign static values in the constructor, put those in the property list directly. Use the constructor to pass new values to the class properties. I suggest using an array for that.
public function __construct($config = array())
{
foreach( $config as $key => $val ) {
if(isset($this -> $key)) {
$this -> $key = $val;
}
}
}
3. You don't use array indexes properly. It should be either integers or strings. So this
Should really be this
4. Your final function, send_form(), outputs instead of just returning a result (boolean or string). If you returned instead of outputting you can send different output depending on the situation, or do other things with it (like logging silently, redirecting, etc)