what is a postal contract
(November 2011). The posting rule (or mailbox rule in the United States, also known as the postal rule or deposited acceptance rule) is an exception to the general rule of contract law in common law countries that acceptance of an offer takes place when communicated.he rules of contracts by post (postal rules) includes the following: 1  An offer made by post/letter is not effective until received by the offeree. 2  Acceptance is effective as soon as it is posted.