How to prevent Service Desk customers from receiving Tempo notifications?

[Esther Strom]

Our service desk install is set up to use public sign-up for service desk to allow our external customers to submit issues. The problem is, those users, even though they are not employees and don't become licensed users, are being included in the default workload scheme in Tempo, which means they're getting timesheet notifications. (Note that our service desk install was set up by an outside consultant that we no longer work with, so I'm not sure if something was done incorrectly, or if this is expected behavior.)

I found another discussion here about a different problem that suggested adding specific users to a special, no-hours workload scheme. Unfortunately, we have thousands of these users, and there's no bulk action available.

Is there any way to prevent specific user types from being included in the Tempo scheduler emails? They're not part of any group, and the only way I can differentiate them (aside from not being part of any group) is that they are all part of the Service Desk Customers role in our various service desk projects (we have several.)