Katherine mailed Paul an offer with definite and certain terms and that was legal in all respects stating that it was good for 10 days. Two days later she sent Paul a letter by certified mail ( time stamped by the postal service at 1:14pm) stating that the original offer was revoked. That evening Paul emailed acceptance of the offer to Katherine. She immediately phoned him to tell him that she had revoked the offer that afternoon, and he would surely receive it in tomorrow's mail. Was the offer revoked by Katherine?