Where to put an email function

[eluser]sophistry[/eluser]
found this code by wiredesignz that illustrates multiple inheritance in CI controllers nicely.
see

Code:

application/libraries/MY_Controller.php
class MY_Controller extends Controller
{
    function MY_Controller()
    {
        parent::Controller();
    }
application/controllers/main.php
class Main extends MY_Controller
{
    function Main()
    {
        parent::MY_Controller();
    }

the top post on this page of this enlightening OO-design oriented thread from a few months back.