Please send comments and suggestions to our post office box.请把意见和建议寄到我们的邮政信箱。The key may be a box number or a department to which the reply is to be addressed.索引标号可以是某一邮政信箱号码，也可以是某一指定接受回信的部门。The letter was sent to a post office box in New York.信件寄到了纽约的一个邮政信箱里。