所有信件将按绝密处置。

All letters will be treated with complete confidentiality.

《牛津词典》

邮局里的人员将信件按寄送地点分类。

Men in the post office classify mail according to places it is to go.

《新英汉大辞典》

任何信件都应该按所需邮资贴邮票。

All letters must be stamped with the correct postage.

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