When an object with a finalize method becomes unreachable, it is put on a queue to be processed at some later time.

当包含finalize方法的对象变得无法访问时，它会被放入一个将在以后某个时刻处理的队列上。

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This message was undeliverable due to the following reason: Your message could not be delivered because the destination server was unreachable within the allowed queue period.

以下理由导致您的信件无法寄达：由于无法在允许的伫列周期之内与目标伺服器取得连线，导致这封邮件无法寄达。

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