The general rule is that the acceptance of an offer must be received by the offeror before it is complete, but there is important exception in the case of acceptance by letter which is complete when the letter having been properly addressed and stamped is posted
On the other hand the revocation of an offer is only effective when it is actually received by the offeree. In this problem before us since Y made his offer in writing, he impliedly authorized the use of the post in his reply and so there was a complete contract when X posted his letter of acceptance. Y’s letter of revocation reached X on Wednesday, i.e. a day after X had already communicated his acceptance. It is therefore submitted that there is a binding contract between X and Y, and Y would be liable for breach of contract.