A contract by correspondence is concluded at the moment and place where you, having received the offer, respond by accepting it (art. 24). It is therefore not the receipt of your response by the other party that matters, but the moment you respond affirmatively.
An important clarification regarding the deadline:
- If the offer fixes a deadline for acceptance, the party who made it remains bound until the expiration of that deadline; it is released if your acceptance does not reach it within the fixed deadline (art. 29).
- If the offer does not fix any deadline, the author remains bound until the moment when a response, sent within a reasonable moral deadline, would normally have reached him (art. 30).
Also pay attention to the form of your response: a conditional or restrictive response does not constitute acceptance. It is equivalent to a refusal accompanied by a new proposal (art. 27). Conversely, your response conforms to the offer if you simply say that you accept, or if you perform the contract without making any reservations (art. 28).
In short: respond clearly "yes", within the deadline, and the contract is formed.
This is general legal information, not legal advice. For advice on your specific situation, consult a lawyer admitted to the Bar in Morocco.