I'm one of the dial-up people you mentioned. When somebody sends me one of those "this is 2 cute, you have to see this" emails with dozens of pictures of cats or clouds shaped like Jesus, it takes ten minutes to receive, and in the meantime I can't send or receive anything else.

Yes, I can use webmail and delete stuff before I open Outlook Express, but that's a pain, too.

I've sent a few friends and relatives a polite "I enjoy most of your forwards, but I'm on dial-up so please don't", and most of them remember...for a while.