Day 1: BookCo’s manager e-mails an offer to sell a rare first edition of For Whom the Bell Tolls, signed by Hemingway, for $50,000 to Rare Book Retailer (RBR).

Day 2: RBR receives the offer, prints out the e-mail, writes “ACCEPTED, one Hemingway book for $50,000, RBR Manager,” and faxes BookCo the acceptance.

Day 3 (9:00 a.m.): BookCo’s receptionist receives RBR’s fax.

Day 3 (12:00 p.m.): BookCo’s manager calls RBR to revoke her offer.

Day 3 (1:30 p.m.): The RBR acceptance fax is delivered to BookCo’s manager.