To maintain effective coexistence with previous versions of
Exchange, it is important that you understand the benefits,
limitations, and considerations when operating your Exchange
organization in mixed mode.
Benefits of Mixed Mode
Running your Exchange organization in mixed mode ensures future
interoperability between Exchange 2000 and previous versions of
Exchange. The benefits of operating in mixed mode include the
Seamless interoperability between Exchange 2000 servers and
Exchange 5.5 servers.
All Exchange 5.5 directory service objects such as servers and
connectors are replicated to Exchange 2000 and are displayed in the
System Manager snap-in.
Routing between Exchange 2000 and Exchange 5.5 is
Exchange 2000 can use existing Exchange 5.5 connectors and
gateways to connect to foreign e-mail systems and route e-mail
Both Exchange 5.5 objects (users, custom recipients, and
Distribution Lists) and Exchange 2000 objects (users, contacts, and
groups) can be managed from Active Directory.
You have the option to install Exchange 5.5 servers at a later
Public folders replicated between Exchange 2000 and Exchange
5.5 can be securely accessed from clients on either system.
Limitations of Mixed-Mode
When operating your Exchange organization in mixed mode, there
are a number of limitations and issues you must consider.
Note Because of the
limitations of mixed-mode operation, you should not operate in
mixed mode if your organization uses Exchange 2000 servers and if
you are sure your system will not be connecting to previous
versions of Exchange.
Consider the following limitations and issues when operating in
Exchange 5.x sites are mapped directly to administrative
Administrative groups are mapped directly to Exchange
You can only move mailboxes between servers that are in the
same administrative group.
Routing group membership must consist only of servers installed
in the administrative group that is defined with the routing
Note In an Exchange
5.x site, not only do you manage the servers as a single
group, but all servers have full-mesh
connectivity for sending messages to one another. However, when an
Exchange 2000 organization is in mixed mode and Exchange 5.x
sites are mapped one-to-one with administrative groups, you can
subdivide the routing structure for the Exchange 2000 servers in
the collection using routing groups. A server cannot belong to a
routing group that is held under a different administrative