And every month he mailed a postal money order.

每都会寄一张邮政汇票。

He's most likely in jail for stealing a postal order.

有可能因为偷了一张邮政汇票而坐牢。

There were a dozen of them hell-bent on stealing postal orders.

当时可是有一大群人拼命想偷走邮政汇票呢 邮政汇票是指付给某人一定金额的凭据。