– Pursuant to Clause 1c, Section I of Circular No. 108/TT-PC dated May 19, 1990 of the State Economic Arbitration guiding the signing and performance of economic contracts:

Contracts are signed in writing or by transaction documents. Contracts signed in writing means that both parties sign together or one party signs first, the other party signs later, but they both sign on the same document. Contracts signed by transaction documents only include documents such as official letters, telegrams, offer orders, purchase orders. (Other forms of transactions such as letters, phone calls, referrals, receipts, invoices, train tickets, passbooks, etc., are not considered transaction documents for signing economic contracts, but only serve as evidence in the economic contract relationship, which has been signed in writing or by transaction documents, dispatches, telegrams, offer orders, purchase orders).

Pursuant to the above provisions, the reference principle is that only the offer or purchase order signed by both parties (maybe via email) confirming the purchase and sale information; and clearly stipulate the rights and obligations of the parties in the trading and economic relations; is considered a form of economic contract.