O.C.G.A. § 13-3-3: When written acceptance of offer made by letter takes effect; acceptance of offer containing alternative propositions.

If an offer is made by letter, an acceptance by written reply takes effect from the time it is sent and not from the time it is received; hence, withdrawal of the offer by the offeror after that time is ineffective. If an offer contains alternative propositions, the party receiving the offer may elect between the alternative propositions.