AC Mailbox alwasy return false problem

bool WorldSession::CanOpenMailBox(uint64 guid)
{
 if (IS_CRE_OR_VEH_OR_PET_GUID(guid))
    {
        if (!_player->GetNPCIfCanInteractWith(guid, UNIT_NPC_FLAG_MAILBOX))
            return false;
    }
    else
        return false;

    return true;
}