Well, since your this one was already sent, all i can say is that dusting with Safe Travel Sachet Powders would be useful for your next envelope or package.
SPD-HOO-SAFE
Safe Travel Sachet Powders
$5.50
You can order right here in the Forum by clicking on the blue Add To Cart button.
For now, if you are a Catholic, a quick prayer to Saint Christopher for travel safety and Saint Expedite for rapid delivery of the mail would be sufficient. You could light a candle to them and promise a reward upon completion of the task. Rewards to Saint Christopher include helping travellers and/or publishing his name -- Saint Expedite prefers a little slice of pound cake and a bouquet of flowers on the altar.