You can make a stylus for a capacitive screen by making a capacitive stylus. My wonder is why one would make using a stylus a more difficult and expensive proposition in order to have a lower quality screen input.
How many use cases are there for needing a so precise stylus? Apart from drawing, I can't really think of anything that hasn't benefited from capacitive screens + fingers...
If you need a stylus to read mails, use the web or normal stuff, you'll probably need a better UI, not a stylus
If you need a stylus to read mails, use the web or normal stuff, you'll probably need a better UI, not a stylus