TABLE OF CONTENTS Using the techniques described already for mailbox migrations, you are restricted to performing moves within a single organization these techniques cannot be used for interorganization moves. With the large numbers of acquisitions and divestitures that many organizations seem to incur these days, the problem of migrating from multiple and distinct Exchange 5.5 organizations to a single Exchange 2003 organization is a common one. For interorganization interoperability and migration projects, there are several challenges to be overcome, notably:
Directory synchronization
Mail flow
Mailbox content migration
Public Folder interoperability
Mail flow is probably the easiest problem to overcome with interorganization environments. SMTP is usually the simplest approach, but care must be taken if a shared SMTP address space is to be used across multiple separate Exchange organizations. Often X.400 is a good mechanism to use here to avoid mail routing issues, but a centralized hub-and-spoke architecture can be used even with SMTP.
Several tools and utilities are available for this kind of migration, and the most commonly used one has for some time been the Mailbox Merge Wizard (formerly known as ExMerge). However, the Mailbox Merge Wizard only deals with actually moving mailbox data, not the other associated problems with interorganization migration.
Other tools you should consider for use within environments such as this include the Active Directory Connector with interorganization CAs, which will perform directory synchronization, but do note that although you can use interorganization CAs, such CAs will not synchronize Exchange 5.5...
