If there is a history of contractual relations between the two parties and the offeree does not comment on a proffered contract, their silent acceptance may be inferred from past history. However, a series of contracts must exist for this standard to be applied.
The terms of acceptance, such as requiring that acceptance be faxed or mailed to the offeror, may be laid out in the text of the offer. These are acceptable restrictions that can be placed on conditions of acceptance and are not considered to place an unreasonable burden upon the offeree. The acceptance must be returned in such a way that meets or surpasses the level laid out by the offerror.
If the acceptance is sent through the postal system, it is considered to be in effect as soon as the postage on it has been paid, whether it is delivered to the offeror or not. This is the case because the acceptor fulfilled a reasonable attempt to convey their acceptance. In addition, forcing the acceptor to ensure that the postal service completed delivery of the acceptance is seen as placing an unfair burden on the acceptor. The one exception to this “mailbox rule” is in contracts which specify that the contract is conditional on receipt of acceptance.
The acceptance must be made in a timely manner. If the offer does not give a deadline by which the contract must be accepted, the courts have decreed that the acceptance must still be in a reasonable amount of time. It is impossible for acceptance to be delayed forever.