I have been involved in a couple of discussions concerning online forums. There are 2 distinct styles of forum, the php style here, which allows multi dimensional discussions , and the older linier style still used by Yahoo, and interestingly Facebook.
The discussions related to signatures. On php forums these can be set up automatically, so you can put all your brain power into the message, not having to remember to sign the message.
As I use a pseudoname for forums this links this to my real name without having to remember to do it.
My Hotmail account also has this feature, so that's easy for email. Unfortunately Yahoo does not have this option(unless its well hidden in a badly designed system) so most of my messages tend to go unsigned, unless I reply to the email which is sent whenever a message is posted on that forum. I tried this and it worked, but I did not feel I was part of the forum. When you are actually logged onto the Gnatterbox, you feel like you are in a room of friends. That is a very important part of online forums.
I have not even looked to see whether it is possible to post messages here via email, but I would not want to. Chances are I would not see something else on the forum which was relevant, and might have changed what I said.
Personally I would not like to see a link between email and online forums, except it useful sometimes to tell you there is a new message. For a busy forum that then generates a lot of messages, so clogs up my email account. I prefer to actually look at the forum, and it is far more enjoyable than just reading emails.
I am sure this is something either being investigated by psychologists or something they should be.