Hmmm … the Smarthost is an outsourced virus/spam scanner. I assume that you are wanting to route messages originating from inside to destinations outside your network. The only way that could work is to set up a separate SMTP service that isn’t tied to the domain/Exchange policies and “smarthost.” Of course, this is completely dependent on your network policy relating to unauthorized SMTP services/servers. The purpose of the outsourced scanning system is to prevent the proliferation of infected or spam messages originating from your network/organization. Thus, reducing your organization’s potential liability and reputation. Bypassing that would be dangerous and your network security policy very likely forbids this. My own network security policy requires that all email (incoming and outgoing) goes through the scanner and there are no other authorized SMTP services/servers. No exceptions.