Posting rule

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. Under the posting rule, that acceptance takes effect when a letter is posted (that is, dropped in a post box or handed to a postal worker). In plain English, the "meeting of the minds" necessary to contract formation occurs at the exact moment word of acceptance is sent via post by the person accepting it, rather than when that acceptance is received by the person who offered the contract.