I recently discover a great tool for testing subscriptions and workflow notification in System Center Service Manager. The tool is called Papercut, and can be downloaded from papercut.codeplex.com.
Papercut is a simplified SMTP server designed to only receive messages with a GUI on top of it allowing you to see the message it receives.
What this allows you to do is to test your notifications in Service Manager without needing to actually send out messages to users. I find this tool especially handy during deployments. Now you can configure all of your templates and subscriptions with the actual user information and not have to worry about making sure everyone knows these are test messages.
To use the tool all you need to do is download and extract the zip file from http://papercut.codeplex.com/releases. Then simply launch Papercut.exe. Next you need to set the E-Mail Notification Channel in SCSM to point to the machine running Papercut.exe. I normally just run it from the management server. After that, your notification will begin to appear in the Papercut app.