Please note that there is a difference between performance and preparation. A bidder cannot revoke an offer as soon as the bidder has begun to be rejected. However, if the bidder has only started preparation but has not yet begun the representation, the bidder may revoke the offer. For example, if an acceptance is sent late, it is ineffective as a hypothesis. However, it has the legal weight of a counter-offer and the supplier can accept or reject the counter-offer. Provided the receipt has been shipped on time, it must also be properly shipped. Essentially, this means that the reception must be dispatched by an appropriate means of communication. Please note that in such a case, acceptance is not valid, but it has the weight of a counter-offer. As mentioned above, this idea is codified by the “mailbox rule,” which states that acceptance is effective when shipping before the supplier has even received it. (The minor derogation from this rule relates to option contracts for which acceptance is effective only when they have been received by the supplier.) See Cities Service Oil Co., v. National Shawmut Bank, 172 N.E.2d 104 (Mass.
1961). The “reflection rule” states that if you must accept an offer, you must accept an offer accurately and without change; If you change the offer in one way or another, it is a counter-offer that will cancel the original offer and cannot be accepted at a later date.  Please note that a firm offer becomes irrevocable, even if the offeror opposes in nominal terms only in exchange for the promise to leave the offer open. For example: Counter-offer:A new offer that varies the terms of the initial offer and therefore refuses the initial offer. As a general rule, if the offer results in a unilateral contract, the offer cannot be revoked once the bidder has begun to execute it. As a general rule, no particular form is required for adoption. In Empirnall, the court tested as follows: “If a reasonable viewer would consider the bidder`s conduct, including its silence, as a signal to the supplier that its offer has been accepted.” With respect to unilateral contracts, the rule is that the bidder`s acceptance power is not terminated by the death or incapacity of the bidder as soon as the bidder has begun its performance.