I would like to be notified by email when someone comments on my question or answer, or when there is a later comment on same item I've commented on.

E.g., let's say I ask a question, then someone comments on it, then I answer that comment with my own comment. If there is another comment after that, I would really like to know about it via email. I know that the notification mechanism exists in some form, because when I log back into the website, I see a red bar at the top notifying me of the new comments; I just can't figure out how to get notified by email.

An RSS feed would also work, but would be less ideal.