Postal rule

Postal Acceptance Rule The mailbox rule or the postal acceptance rule (also called deposited acceptance rule) is a term of common law contracts which determines the timing of acceptance of an offer when mail is contemplated as the medium of acceptance. The general principle is that a contract is formed when acceptance is actually communicated to the offeror. The mailbox rule is an exception to the general principle. The mailbox rule provides that the contract is formed when the letter of acceptance is placed in the (outgoing) mailbox.
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A rule of contract law that makes an exception to the general rule that an acceptance is only created when communicated directly to the offeror. - (read more on Postal rule)