None of the people I have met in recent years write letters. My mother kept a 40+ year correspondence with her brother until his death a few years ago. I even wrote him letters and I have kept his replies. I don't think I was the only person in my class at school to apply for penpals but I didn't hear of any long lasting correspondence. I had a correspondence with a friend from university but lost touch by either of us moving.
I often write letters while in a cafe over a panad (cuppa) and have received pleasant comments. One cafe worker mentioned wanting her own penpals and I gave her a couple of links to try, mentioned in a previous blog post of mine. When I go to a post office to buy the special issue stamps, they don't believe that I am just a collector and the stamps I buy are destined to be used for postage, what postal stamps are intended for.
Other than your penpals and people you have contact with on a penpalling forum/blog, do you know anyone (perhaps from work, school, friends, family) who writes letters?