I'm thinking it may be a good idea to "pin" permanently a post at the top of each forum, that has an explaination that this board now requires registration to post. And the reasons why.
It may confuse some of those who don't visit very often, or first time visitors.
Maybe also an explaination in the same message that no one can see your email address, unless you wish, and other privacy concerns.
Anyone have any other possible concerns that could be addressed in a message I describe?
Brandon