I'm not sure how to post by email, but once you are subscribed to a thread it is easy to reply via email. I just tested it out in the "in print articles..." thread. works perfectly.
I'm not getting new posts in my inbox anymore. Well, some I get, others not so much. I've gone to my preferences and checked "email" for every one. Anyone else having this problem?
I think I might have a hint. You will not get emails for the whole forum. That doesn't seem to be an option in the notification preferences. You must 'bookmark' a discussion and then you will receive emails for it (assuming you checked that preference). To bookmark a discussion, click on the star next to it, which will then turn yellow.
It looks like you can also bookmark entire categories. Click on the 'Categories' link on the upper left and click on those same stars.
There is also a notification category 'my discussions'. I suppose those are ones that you started by clicking 'New Discussion' on the upper left.