A receive Connector is linked to a Send connector. When the Receive Connector gets a message, it delivers the message to send connector.
1-->2-->3-->4Exchange Hub Transport Server has 2 receive connectors and 2 send connectors.
ON exchange 2007 server: CHINA
Antispam server: Canada.itsme.com
New-SendConnector -Name mySend -LinkedReceiveConnector "Default China" -SmartHosts "canada.itsme.com" -SmartHostAuthMechanism "NONE" -DNSRoutingEnabled $False -MaxMessageSize unlimited
Pay attention to the port number assignment.
The send connector does not have a name space.
When a internal user sends mail, 1 -->2 route is selected as usual.