>I have a web service set up to send email. We have to set up each client individually on our web server to allow for programmatic emails. We set up this web server and all automated emails will go through the web service. I am creating a utility class to interface with the web service, but I don't want the client to interface with the web service directly.

Raw curiosity, the webservice and the utility are in the same DLL or in different DLLs?

In any case if you can't hide the web service you could always put some form of authentication code into it that would verify that the caller is your utility.