friends_notification_new_request( int $friendship_id, int $initiator_id, int $friend_id )

function friends_notification_new_request( $friendship_id, $initiator_id, $friend_id ) {
	if ( 'no' == bp_get_user_meta( (int) $friend_id, 'notification_friends_friendship_request', true ) ) {
		return;
	}

	$unsubscribe_args = array(
		'user_id'           => $friend_id,
		'notification_type' => 'friends-request',
	);

	$args = array(
		'tokens' => array(
			'friend-requests.url' => esc_url( bp_core_get_user_domain( $friend_id ) . bp_get_friends_slug() . '/requests/' ),
			'friend.id'           => $friend_id,
			'friendship.id'       => $friendship_id,
			'initiator.id'        => $initiator_id,
			'initiator.url'       => esc_url( bp_core_get_user_domain( $initiator_id ) ),
			'initiator.name'      => bp_core_get_user_displayname( $initiator_id ),
			'unsubscribe'         => esc_url( bp_email_get_unsubscribe_link( $unsubscribe_args ) ),
		),
	);
	bp_send_email( 'friends-request', $friend_id, $args );
}