send_email = function() {
    var bt_env_email = document.getElementById("bt_env_email");
    var box_enviar_email = document.getElementById("box_enviar_email");
    var bt_close_send = document.getElementById("bt_close_send");

    bt_env_email.onclick = function() {
        if (box_enviar_email.className == "") {
            box_enviar_email.className = "active";
        }
        return false;
    }
    bt_close_send.onclick = function() {
        box_enviar_email.className=box_enviar_email.className.replace("active", "");
        return false;
    }
}

/*function addEvent( obj, type, fn )
{
	if (obj.addEventListener)
		obj.addEventListener( type, fn, false );
	else if (obj.attachEvent)
	{
		obj["e"+type+fn] = fn;
		obj[type+fn] = function() { obj["e"+type+fn]( window.event ); }
		obj.attachEvent( "on"+type, obj[type+fn] );
	}
}*/

addEvent(window, 'load', send_email);