silverstripe-blog/code/extensions/BlogPostNotifications.php

<?php

/**
 * Customise blog post to support comment notifications.
 *
 * Extends {@see BlogPost} with extensions to {@see CommentNotifiable}.
 */
class BlogPostNotifications extends DataExtension {
	/**
	 * Notify all authors of notifications.
	 *
	 * @param SS_List $list
	 * @param mixed $comment
	 */
	public function updateNotificationRecipients(&$list, &$comment) {
		$list = $this->owner->Authors();
	}

	/**
	 * Update comment to include the page title.
	 *
	 * @param string $subject
	 * @param Comment $comment
	 * @param Member|string $recipient
	 */
	public function updateNotificationSubject(&$subject, &$comment, &$recipient) {
		$subject = sprintf('A new comment has been posted on ', $this->owner->Title);
	}
}