End-of-chapter questions: Answer Guidance 3.2

A good answer to this question requires you to engage critically with the discussion in section 3.3.4. It also raises the broader question of what the default rules of contract law should be. Well-advised commercial parties are typically able to draft around clear rules if necessary, but what should the position be for those who do not or are not so well-advised? Does the postal rule serve any satisfactory business purpose?