My wife, Anne, recently completed transcribing to the computer letters she wrote to her mother in the 60s, 70s and 80s. These letters told of our early days in Canada, and of our slowly coming to grips with autism and Adrian. When we first emmigrated, it was far too costly to phone England, except in an emergancy situation. Letter-writing, using the aerogram flimsies, was the best medium to keep in touch. And those letters now provide a great record of what we did in those days, and what Anne felt about the situation (at least, in a self-edited form for her mother's pleasure.)
Today, we think nothing of sending an email to relatives in England. But those missives are so ephemeral. It is unlikely such mesages will be the valuable archival material seen in those letters sent home to Mum.
For several years now we have sent an annual Christmas Newsletter by email to all kinds of friends and relatives, with hard copies to those without email addresses. Anne has conscientiously added those Newsletters to the archival records of the computer as well as keeping hard copies. Recent experiences with searches for copies of old photographs on the computer show that such archival efforts may be in vain. As we updated from one computer to another, records have been lost. The written word still has its value.