Bella operates a business selling rare coins and conducts much of her business through the post.On Monday she wrote separate letters to Edward and Jacob, offering to sell them a Roman coin for $5,000. Edward received this letter of offer at 5pm on Tuesday and immediately posted a letter of acceptance and money order to Bella. Jacob also received the letter of offer on Tuesday and went to Bella's shop at 9am on Wednesday and happily bought the coin for cash. On Thursday, Bella received Edward's letter of acceptance and consequently Bella telephoned Edward and informed him that she had already sold the coin to Jacob. Edward is certain that he is entitled to the coin.

Is Edward correct? Advise Bella and give reasons for your answer. Would your answer be different if Bella's offer had been communicated by email?