I have just completed the addition of a private messaging option for registered
Discussion Forum users. By visiting your 'private message in-box' (on the main forum topic list) you can send and receive messages to/from other forum users without the need for emailing them. If you have any new messages, you will be alerted the next time you log on.
If you feel the need, there is an option to ignore users, but hopefully it'll not be necessary to worry about this.
However, please remember that this is still a discussion forum, so please keep posting in the public forum too - just use this new facility to send a message to a particular user if it is of a private nature.