I was wondering whether something similar to vessal games (playing whfb) on the internet/via email would be something that this forum would be interested in and how easy it would be to implement?

hmm sounds interesting.. and quite possible to me

I'm not entirely sure I understand some important aspects of your idea.

Do you mean you wish for a central server/online map to which you could connect with the VASSAL Games engine? So.. we'd have like one giant campaign map?
Or do you mean to simply ping people here for interest and get a group going who play the game through the VASSAL system... perhaps with one central map as being "the Druchii map"?