Under the mailbox rule, when is an acceptance effective if no method is specified?

• A. Upon dispatch (posting).
• B. Upon receipt by the offeror.
• C. On the next business day.
• D. Only after the offeror receives it.

Answer: (A)

Under the mailbox rule, when no method of acceptance is specified, an acceptance becomes effective the moment it is mailed, as long as it is properly posted. The idea is to fix the timing of formation to avoid disputes over when the contract is formed, so the offeree isn’t penalized for postal delays. If you mail your acceptance on Monday, the contract is formed on Monday, even if the offeror doesn’t read it until later or never receives it. This shifts the risk of loss or delay to the offeror once the acceptance is properly mailed.

If the statement of how acceptance should occur isn’t given, any reasonable mailing method is acceptable, and the act of putting the acceptance in the mail is what binds you. This is why other options—waiting to be received, or requiring the offeror to receive it before it is effective—don’t fit the rule. The key takeaway is that proper mailing closes the deal at dispatch, not upon receipt.