The response is valid. “Delivery” is a defined term and the answer to the question is found in the Delivery Paragraph (6) itself.

Assuming we are talking about an email transmission, Delivery is considered accomplished/or deemed to have occurred when sent by email, when there is a tangible record of the transmission (i.e. when the agent can show via their sent mail time stamp that it was sent prior to any deadline).

This is to prevent parties to a contract from refusing Delivery or avoiding it, purposefully, beyond the expiration of a deadline, a behavior the contract also prohibits expressly. The same concept exists for let’s say hand delivery or paper mail. They are considered delivered not when received (or picked up from the mail or a drop box), but when actually delivered to a destination that is specified in the contract for delivery.