Yes and no. They may subconsciously pick it up if they are sensitive to such things. They may dream of you. Or they may feel a pull to contact you as long as you include that you want them to contact you urgently.
You'll need to put emotion into your words and really impress your thoughts into the letter. And when you burn it, you should be outside so that the smoke flies straight up into the air. As it does, ask the spirits of air to take your words to (person's name). It's also best that you clearly visualize the person during the entire thing. I would personally consecrate the fire with a pinch of tobacco before burning and give an additional offering after burning the letter to the four winds/directions.