RoutingAgent.OnResolvedMessage event

The OnResolvedMessage event occurs after all the recipients of the message have been resolved and before routing is determined.

Namespace:  Microsoft.Exchange.Data.Transport.Routing
Assembly:  Microsoft.Exchange.Data.Transport (in Microsoft.Exchange.Data.Transport.dll)

protected event ResolvedMessageEventHandler OnResolvedMessage

In the OnResolvedMessage event, you can override the default routing behavior by using the SetRoutingOverride method to set the per-recipient RoutingOverride property.