When mail is the authorized means of acceptance stated in a valid offer, under the Mailbox Rule, when is acceptance effective? When reasonable as determined by the reasonable person standard Upon receipt by the offeror When signed by the offeree When dispatched (dropped in the mailbox) When an offeree alters the terms of the offer, the new terms are considered a counteroffer and thus a rejection of the original offer and the offeree becomes the offeror. Proper acceptance requires accepting the exact terms of the offer. This rule is known as: Mirror Image Rule Strict Performance Rule Bargained-for Consideration Rule Unequivocal Acceptance Rule