There is the possibility of using central adressbooks by adding the source of serverdatabases (e.g. mail/in, adressbook) in a notes.ini entry e.g.
This works fine, as long as the server works. As soon, as the server is not reachable any more, the specific notes client can not send or adress a mail any more.
This could be fixed by having the possibility of using the clustername as server or by expanding the clusterfunction in that area.