I concur, with the following additional reasons. First, depending on what you meant by "mess up": there's a chance they're not trustworthy (would read something you don't want read), and there's also a chance they screw up (and lose what you want sent - or send it when it shouldn't be sent).

Perhaps an even bigger thing for me is that an email seems so... off-hand, informal. I think if a friend/relative/etc died and an email was automatically sent to me from them I would feel a lot less... less something, can't quite think of the word, than if I got a properly written letter. Less sentimental I guess, less appreciative of it.