function bp_activity_new_comment_notification( $comment_id = 0, $commenter_id = 0, $params = array() ) {
	$original_activity = new BP_Activity_Activity( $params['activity_id'] );
	$poster_name       = bp_core_get_user_displayname( $commenter_id );
	$thread_link       = bp_activity_get_permalink( $params['activity_id'] );

	remove_filter( 'bp_get_activity_content_body', 'convert_smilies' );
	remove_filter( 'bp_get_activity_content_body', 'wpautop' );
	remove_filter( 'bp_get_activity_content_body', 'bp_activity_truncate_entry', 5 );

	/** This filter is documented in bp-activity/bp-activity-template.php */
	$content = apply_filters_ref_array( 'bp_get_activity_content_body', array( $params['content'], &$original_activity ) );

	add_filter( 'bp_get_activity_content_body', 'convert_smilies' );
	add_filter( 'bp_get_activity_content_body', 'wpautop' );
	add_filter( 'bp_get_activity_content_body', 'bp_activity_truncate_entry', 5 );

	if ( $original_activity->user_id != $commenter_id ) {

		// Send an email if the user hasn't opted-out.
		if ( 'no' != bp_get_user_meta( $original_activity->user_id, 'notification_activity_new_reply', true ) ) {

			$unsubscribe_args = array(
				'user_id'           => $original_activity->user_id,
				'notification_type' => 'activity-comment',
			);

			$args = array(
				'tokens' => array(
					'comment.id'                => $comment_id,
					'commenter.id'              => $commenter_id,
					'usermessage'               => wp_strip_all_tags( $content ),
					'original_activity.user_id' => $original_activity->user_id,
					'poster.name'               => $poster_name,
					'thread.url'                => esc_url( $thread_link ),
					'unsubscribe'               => esc_url( bp_email_get_unsubscribe_link( $unsubscribe_args ) ),
				),
			);

			bp_send_email( 'activity-comment', $original_activity->user_id, $args );
		}

		/**
		 * Fires at the point that notifications should be sent for activity comments.
		 *
		 * @since 2.6.0
		 *
		 * @param BP_Activity_Activity $original_activity The original activity.
		 * @param int                  $comment_id        ID for the newly received comment.
		 * @param int                  $commenter_id      ID of the user who made the comment.
		 * @param array                $params            Arguments used with the original activity comment.
		 */
		do_action( 'bp_activity_sent_reply_to_update_notification', $original_activity, $comment_id, $commenter_id, $params );
	}


	/*
	 * If this is a reply to another comment, send an email notification to the
	 * author of the immediate parent comment.
	 */
	if ( empty( $params['parent_id'] ) || ( $params['activity_id'] == $params['parent_id'] ) ) {
		return;
	}

	$parent_comment = new BP_Activity_Activity( $params['parent_id'] );

	if ( $parent_comment->user_id != $commenter_id && $original_activity->user_id != $parent_comment->user_id ) {

		// Send an email if the user hasn't opted-out.
		if ( 'no' != bp_get_user_meta( $parent_comment->user_id, 'notification_activity_new_reply', true ) ) {

			$unsubscribe_args = array(
				'user_id'           => $parent_comment->user_id,
				'notification_type' => 'activity-comment-author',
			);

			$args = array(
				'tokens' => array(
					'comment.id'             => $comment_id,
					'commenter.id'           => $commenter_id,
					'usermessage'            => wp_strip_all_tags( $content ),
					'parent-comment-user.id' => $parent_comment->user_id,
					'poster.name'            => $poster_name,
					'thread.url'             => esc_url( $thread_link ),
					'unsubscribe'            => esc_url( bp_email_get_unsubscribe_link( $unsubscribe_args ) ),
				),
			);

			bp_send_email( 'activity-comment-author', $parent_comment->user_id, $args );
		}

		/**
		 * Fires at the point that notifications should be sent for comments on activity replies.
		 *
		 * @since 2.6.0
		 *
		 * @param BP_Activity_Activity $parent_comment The parent activity.
		 * @param int                  $comment_id     ID for the newly received comment.
		 * @param int                  $commenter_id   ID of the user who made the comment.
		 * @param array                $params         Arguments used with the original activity comment.
		 */
		do_action( 'bp_activity_sent_reply_to_reply_notification', $parent_comment, $comment_id, $commenter_id, $params );
	}
}