no, you are wrong. no such 規定.

never hear that 郵件厚度不夠，升級成priority mail是郵局的規定,

this is not right. no such 規定.

www.usps.com

First-Class Mail :

First-Class Mail gets your mail there fast.

Postcards, letters, large envelopes (flats) and small packages can be sent using First-Class Mail®. This service, along with Priority Mail and Express Mail, is ideal for sending personal correspondence, handwritten or typewritten letters, and bills or statements of account. It may also be used for advertisements and lightweight merchandise. First-Class Mail prices are based on both the shape and weight of the item being mailed. For items weighing more than 13 ounces, use Priority Mail.

所有跟帖： 

• well, figure out yourself: http://www.usps.com/prices/first-clas -小小愛茉莉- ♀ (54 bytes) () 11/13/2009 postreply 13:58:44

• actually you are completely wrong on this issue -遠唯一- ♂ (224 bytes) () 11/13/2009 postreply 14:09:23

• 問題找麻煩的郵局營業員不是找重裏的茬，是找郵件體積的薦。 -小小愛茉莉- ♀ (0 bytes) () 11/13/2009 postreply 14:13:55

• you are wrong, if郵件體積is big, you need to use priority mail -遠唯一- ♂ (158 bytes) () 11/13/2009 postreply 14:19:14

• 此規定找到了，我很早以前看過 -小小愛茉莉- ♀ (288 bytes) () 11/13/2009 postreply 14:23:19

• 也可以讓你的客戶把她的local PO電話給你，電話過去問問就清楚了。 -小小愛茉莉- ♀ (0 bytes) () 11/13/2009 postreply 14:03:15

• well, anyway, it is strange -遠唯一- ♂ (96 bytes) () 11/13/2009 postreply 14:10:57