int mboxPerGroup = DebugConfig.mailboxGroupSize; return (mailboxId - 1) / mboxPerGroup + 1;
int groups = DebugConfig.numMailboxGroups; return (mailboxId - 1) % groups + 1;
    public static int getMailboxGroupId(int mailboxId) {        int mboxPerGroup = DebugConfig.mailboxGroupSize;        return (mailboxId - 1) / mboxPerGroup + 1;    }