I don't think I'll go into discussing all aspects of it here, because what would be the point of linking to the article if I were going to do that? I will say that my personal opinion in regards to emails is this:
I think out of respect all emails should be kept at least somewhat private. I don't necessarily have an issue with posting the contents of an email provided you remove important information regarding the sender. I think, in most cases, it is wrong to post something with the author's name on it, unless there is a very good reason to do so. In the case of hate mail I have different opinions. When you send hate mail I see that as sacrificing your right to privacy. You've now gone from sending a simple email to sending something with the intention to scare and or hurt. If someone makes the decision to post that email with your general contact information, well, then you should probably accept the consequences of your actions. Sending death threats to someone is not something to be taken lightly. If you're going to send hatemail, expect that it's going to bite you in the *ss.
Anyway, check out that link. It's really interesting.
(Don't click the read more, there isn't any more after this!)