Our company provides subscription IT support to small businesses. Currently, each customer organization has a separate Exchange Server 5.5 server. We're considering migrating our customers to Exchange 2000 Server. However, I'm concerned about the 20-database limit on Exchange 2000 servers. How can I fit more than 20 customers on one server?
The simplest way to combine multiple customer organizations on one server is indeed to give each customer a separate database. However, you're still approaching the problem from an Exchange 5.5 perspective: one private Information Store (IS) to a customer. Exchange 2000 offers much more flexible methods of cohosting multiple customers on one server. First, drop the assumption that each customer must have a separate database. Instead, use the tools described in Microsoft's hosting documentation to create separate Global Address Lists (GALs) and recipient policies for each customer. Each customer will assume it has a dedicated Exchange server, while you benefit from economies of consolidation because you've grouped your customers' mailboxes on a smaller number of larger servers. In addition, because hosting 20 databases on one server is resource-intensive, you're better off using separate GALs and recipient policies.