One of the exceptions to the rule on acceptance and communication derives from the postal rule.
The postal rule applies to non-instantaneous modes of communication. These include the post and telegram (Cowan v O’Connor (1888). The rule is that acceptance takes place when the offeree sends their acceptance, not when it is received by the offeror. The rule is an exception to the rule on communication because it means that acceptance can be made without it being communicated to the offeree.
The rule was developed in Adams v Lindsell (1818)
Watch this video to learn more about the postal rule and find out the facts of Adams v Lindsell (1818).