routing group

A collection of Servers running Exchange 2000 that can transfer messaging data to one another in a single-hop without going through a bridgehead. In general, Exchange computers within a single routing group have high-bandwidth, resilient network links between each other.

Additionally, a routing group defines the boundary for public folder access. [Exchange 2000]

A collection of Exchange servers that have full-time, reliable connections. Messages sent between any two servers within a routing group go directly from source to destination. Routing groups are optional and are not visible in Exchange System Manager unless they are enabled. [Exchange 2003]

In Exchange Server 2003 and Exchange 2000 Server, a logical grouping of well-connected Exchange servers between which no connector is required for message transfer. In Exchange Server 2007, all Exchange servers reside in a single routing group, regardless of their location. The Exchange 2007 routing group only exists when Exchange 2007 is installed in an existing Exchange organization and is created to allow Exchange 2007 to coexist with earlier versions of Exchange Server. [Exchange 2007]