I was trying to fix a WordPress Post Notification plugin to include the post author in the emails subject. Instead of inserting the author name it was leaving the @@author in the subject.
A little digging around found me the solution -
In sendmail.php->post_notification_create_email(), find -
$subject = get_option('post_notification_subject');
and add a new line after that -
$subject = str_replace('@@author', $post_author, $subject);
Ref – Post Notification forum