Well, I know it means more to me when I send a card or letter than an email (partly because of the extra effort). So it means more to me to receive one as well. Also probably more than half the people I communicate with regularly are not regular e-mail users, even if they have an address. I just think it's for different purposes. Quick notes, information-based, SMS or email; communication - letters or cards.
[Proj] You don't think staying in touch with your aged relatives who are not on the Internets is worthwile in itself? Me, I like sending post cards, but not too many or too often. I defaulted out of Postcrossing recently. In other news, I suck at lecturing. Really and truly.
[Néa] *thinks for a moment*. Mm. Not really - for them or me. [pen] I have friends whom I sometimes don't see for a couple of years, or more. It sounds like in your case it's necessary to send a card or something in order to maintain the friendship subscription (whether used or not). In my case I'm very happy for someone I like to show up again after a couple of years of not calling or writing. I don't require them to ping me in the interval, because it would be a waste of both of our time (at least until they or I are ready to re-engage - and also a waste if one of us is no longer really interested).