dont edit the core code function… use the hooks on it to adjust as you want…
if you look at the code, you will see some apply_filters() calls… you can hook into those to change stuff without editing… are you familiar with how wp api works? if not, see: http://codex.wordpress.org/Plugin_API
those are filters… so you can change the data… so for example, to change the subject, do something like:
add_filter('sph_email_subject', 'my_email_subject', 10, 2);
function my_email_subject($subject, $newpost) {
# do what you want to $subject
return $subject;
}
same for content, but use the sph_admin_email filter… the $newpost array passed in contains all the new post info that was just created.. ie topic name, forum, etc…