> Is there a way to have 2 Listserv servers automatically kept in sync with
> each other?

On Windows, the only method not requiring third-party software would be DFS.
The main technical problem with DFS is that it is not very
bandwidth-efficient, especially if you have large files (in practice, large
lists). If I were Bill Gates, I would improve the granularity of DFS and
then increase its profile for disaster recovery purposes. As it stands, I
don't feel completely comfortable recommending it, at least not for every
scenario.

Since DFS is included with Windows Server, you can try and find out easily
if it works well enough in your environment. I have nothing against any
particular third-party products, I just happen to be familiar with DFS, and
it would be my first test if I were tasked with solving the same problem.

  Eric