英语语法分析

If undelivered, please return to sender.

若无法投递，请退还寄信人。

To ensure prompt delivery of all supplies and to follow up outstanding orders and undelivered portion.

确保所有供应物品及时到货并跟进未解决的订单和未送达的物品。

Undelivered messages may be placed on error queues, interpretation of such messages requires contextual information.

未交付的消息可能放置在错误队列上，每个此类消息的解释都要求使用上下文信息。