@Jerry @debacle @_elena I'm in a similar situation, and I've used a bit of a stick-and-carrot approach where I'm only available on xmpp (or email. nobody seems to have taken up the postcard option :D ), but I've also offered family members accounts on my server, to ease their onboarding.
(for convenience I also host accounts for a few friends, but in that case I have the requirement that they provide the domain, so that they can easily migrate elsewhere if they so decide)