As POA for Mom, I've had to rely on my stash of legal size envelopes, stamps, and return address labels a few times. That is in addition to having to fax things. The world runs on paper even still. Fax machines are still in use, as well as paper, real ink signatures, and postage.
I ran out of legal size envelopes, so I added them to my grocery list. Previous to that, I was using just regular ole' envelopes, mostly to stay in touch with Mom. We have been "faithful correspondents" for years since before I went away to college. My handwriting was so sloppy that I started typing the letters. I knew that she was delighted to receive them - she told me that it was the first thing she opened when she found one in the mail. I wanted her to be able to read them with ease. Short and sweet - one page long. Phone calls were for her to share what was going on in her life. Truth be told, I wanted to hear it. Even though she said I told her otherwise, I never did.
Looking at the plastic bin under my desk is hard. Mother may have misunderstood a thing or two that I wrote to her, and she often "quoted" me incorrectly, but writing her a letter, at least once every week or two, kept me grounded and connected to her. At some point, I will collect all of those letters, that I am sure she never threw away, and add them to the collection of the letters she wrote to me in response. They span years and years as a diary of our life together as mother and daughter.