This was often done in the past via "Christmas Letters," or other annual (or semi-annual) letters. A family would write a one- or two-page letter detailing their major life events and experiences since their last letter, and send it to friends and family they haven't seen or talked to much.

Sending them is a good way to keep in touch with people you wouldn't normally, and receiving them is nice because you can feel like you've never fallen out of communication with your family, even if the Christmas Letters are the only kind you get.