Whenever an offeror fixes a period of time for acceptance the

question arises of when the period begins to run. According to this

article it begins to run from the moment the offer is dispatched, i.e.

has left the sphere of control of the offeror. As to when this occurs

there is a presumption that the time of dispatch is the time indicated in

the offer. For instance, in the case of a letter, the date of despatch will

be the date shown on the letter; in the case of an e-mail, it will be the

time indicated as the sending time by the offeror’s server; etc.

However, the presumption may be rebutted if in a given case the

circumstances indicate otherwise. Thus, if the date shown on a fax

letter is prior to the sending date printed by the fax machine, the latter

date should prevail. Likewise, if the date shown on a letter is later than

the delivery date of the letter, it is clear that the latter was written in

by mistake and should therefore be disregarded.