Supressing Mail notifications

We've written a tool to automatically move code from one stream depending on some results. The tool updates the associated work items with a FYI statement but this means mass emailing to individuals who are subscribed to that work item. The individuals are interested in genuine updates to a work item but not the FYIs ones unless there's a subsequent problem and they want to trace its origin.

This is with RTC V2.

So my questions are related to this:
Is there a way to suppress mail notifications for updates made by a specific user id?
If not, is there a way to programmatically switch off mail notifications and back on so that the tool can switch it off and then turn it back on after its update.
Is there a way to switch off mail notifications for a particular work item (again programmatically).