If the procedure had been reasonable, L would have the advantage of a presumption of attribution of the message. Since it was not, L must prove that M did send the message without the benefit of a presumption. If it can do so, it can enforce the contract. The problem of garbled, misrecorded or otherwise mistaken offers and acceptances is one of long-standing in commercial practice. M requires that L use an unreasonable attribution procedure for transmitting orders and acceptances.
L agrees and adopts the procedure.
It places an order for ten software widgets. Because the procedure is flawed, the message arrives at M requesting 100 software widgets. M ships on that basis. L desires to ship the ninety excess widgets back to M and not pay. One could argue that no contract exists because of mistake.