This is a subtle thing, but can become important. I remember having to coordinate a project with managers in different locations. There was this one manager who was brilliant because she always replied to my group emails with a quick, thank you and will do. It's true, I really did think highly of her because those few words had me believe she was on top of it. And she was. It's such a small thing but can make a big difference when working from a distance and in groups.