Most of us are familiar with the concept of a postcard. By default, they are a simple and lightweight way of staying in touch. Likely few of us send postcards physically (often), which is too bad because they are a beautiful concept.
But you can easily send postcards (virtually). All you have to do is:
That's it.
A lovely thing about this format is it's open! You can do it via text, email, or who knows!