16 Electronic Transactions No. 33 (b) where the recipient has not designated an information system, when the electronic message enters an information system through which the recipient retrieves the electronic message. (3) Unless otherwise agreed by the parties, an electronic message shall be dispatched at the sender's registered place of business and shall be received at the recipient's registered place of business. (4) Where a sender or recipient has more than one registered place of business, his retained place of business shall be the one having the closest link with his underlying operation or, in the absence of such underlying operation, with the principal place of business. (5) If a sender or recipient does not have a place of business, the place of usual domicile shall be taken into consideration. Offer and acceptance (6) The provisions of this section shall apply even though the information system supporting the electronic address of the recipient differs from the place where an electronic message is considered to be received under this section. 21.__(1) Unless otherwise agreed by the parties, an offer and acceptance of the offer may be wholly or partly expressed by electronic means. (2) A contract concluded between parties by means of electronic messages shall be concluded at the time when, and place where, the acceptance of the offer was received by the recipient: Attribution of electronic messages to sender Provided that parties may agree that the contract was concluded at the place of residence of one party or the place of location of the legal entity, who accepted the offer. 22.__(1) An electronic message shall be considered to be that of the sender, if it was sent__ (a) by the sender personally; (b) by an agent of the sender; or (c) by an information system programmed by the sender or on behalf of the sender to send electronic messages automatically. (2) The recipient of an electronic message shall justifiably consider that the electronic message came from the sender and act accordingly if__ (a) the recipient properly applied a procedure previously agreed with the sender for this purpose; or