The mailing list and the Discussion Board can exist together, side by side. It exist a lot of users, they don't like mailing list. For me, i think, it is easier to post in a board for a problem as in a mailing list. Different people, different tasts.
I didn't want to corrupt the mailing list or delete the mailing list or whatever. Its not if better there are two or more ways to get support to couchdb? So you can raise lot of more people.
