胡晓凡 汤文华

二、投邮主义（Mailbox Rule）

1. 定义1

投邮主义，又称“发信主义”，是普通法中确定承诺（acceptance）生效时间的原则。其基本定义为，受要约人以书信、电报对要约进行承诺时，在符合镜像原则的前提下，承诺一经投至邮筒或者交至电报局即发生法律效力（effective upon dispatch）。除了寄送書面承诺，开始履行要约中的义务也是对要约进行承诺的一种形式（acceptance by performance），而根据投邮主义，不论要约人是否意识到受要约人开始履行义务，自履约那一刻起，承诺即生效。

投邮主义仅适用于承诺，而不适用于除承诺外对要约的撤回、修改等。例如，如果原要约人发出撤回原要约（revocation）的意思表示，只有当受要约人收到时才发生法律效力（effective upon receipt）。又如，如果受要约人在收到要约后并未进行承诺，而是将反要约投递至邮筒或交至电报局，则只有在原要约人收到反要约，且将书面承诺邮寄或通过电报发出后，才构成对反要约的承诺（acceptance of counter offer）。在反要约的情景中，原要约人变成了受要约人，而原来的受要约人变成了新的要约人。

下面以LEC真题2为例，来进一步了解投邮主义的应用：

Ted owned bowling lanes and needed to buy some new bowling balls. On February 1， he read an ad from FMA， a major manufacturer of bowling balls， that they were having a special on balls： 40 balls in various weights and drilled in various sizes for $10 per ball. Ted immediately filled out the order form for the 40 balls and deposited it， properly stamped and addressed， into the mail. The very next day， Ted received in the mail a letter from FMA， sent out as part of their advertising campaign， stating in relevant part that they will sell Ted 40 bowling balls at $10 per ball. On February 3， FMA received Teds order. On February 4， the balls were shipped.

On what day did an enforceable contract arise？

A. February 1， the day Ted deposited his order in the mail.

B. February 2， the day Ted received the letter from FMA.

C. February 3， the day FMA received Teds letter.

D. February 4， the day the balls were shipped.

本案例中涉及的双方，Ted是保龄球场地所有者，FMA公司是保龄球的生产商。Ted在2月1日寄出的订货单（order form）是向FMA公司发出的要约，而Ted在2月2日收到的广告（advertisement）是FMA公司发给Ted的要约。2月3日，FMA公司收到了Ted的要约（订货单），并于次日（2月4日）发货。

可以将上述情形总结如下：

·Feb. 1： Ted sent an offer （order form） to FMA.

·Feb. 2： Ted received an offer （advertisement） from FMA.

·Feb. 3： FMA received Teds offer （order form）.

·Feb. 4： FMA shipped the balls.

由上面的总结可以看出，本案例中涉及两个要约（Ted寄给FMA公司的订货单，以及FMA公司寄给Ted的广告）。而真正被接受的要约，是Ted寄给FMA公司的订货单。……