True or False: An acceptance sent in the mail after the offer has been revoked is still valid if it was postmarked before the revocation.

An acceptance sent in the mail after an offer has been revoked can still be considered valid if it was postmarked before the revocation took effect. This is rooted in the "postal rule" of contract law, which states that an acceptance is effective when it is sent (i.e., postmarked), not when it is received by the offeror. Therefore, if the offeror has revoked the offer but the acceptance was sent prior to that revocation, the acceptance is legally binding.

This principle underscores the importance of the timing of communication in contract formation. As long as the acceptance was dispatched before the revocation notice was communicated to the offeree, it holds validity. The rationale is to promote certainty and protect the offeree who may be relying on the belief that an acceptance is valid based on the timing of their response.

In contrast, the other options do not accurately reflect this principle. There isn't a requirement for the original offer to be mail-based for the postal rule to apply, nor does the validity depend on the efficiency of the postal service. The critical factor is the timing of when the acceptance was sent relative to when the revocation was communicated.