I was thinking of leading a Zimbra deployment for a consortium of local colleges to share costs, expertise, etc.

There would be one central LDAP master server, and an LDAP replica at each site. Each site would host their own mailbox server in their own data center connected to their own LAN and SAN.

What happens to the satellite servers if their link to my master server goes down? It would be really nice if they could run their own severable MTAs and IMAP servers. If I understand the architecture correctly, then in theory, in the absence of a master LDAP server, everything but creation of new accounts/forwards/aliases/distribution lists would continue to work.

[How] has the behavior of a multi-server Zimbra deployment been tested? Is this sort of use case envisioned/supported?