MailboxTable::getUserMailboxes

static function getUserMailboxes($userId = null): array
{
	global $USER;

	if (!($userId > 0 || (is_object($USER) && $USER->isAuthorized())))
	{
		return [];
	}

	if (!($userId > 0))
	{
		$userId = $USER->getId();
	}

	$sharedMailboxes = static::getTheSharedMailboxes($userId);
	$ownersMailboxes = static::getTheOwnersMailboxes($userId);

	return $ownersMailboxes + $sharedMailboxes;
}