[rt-users] QueryBuilder: find where LastUpdatedBy 'unprivileged'

[Allen]

We would like to make a Saved Search that will show us all tickets
where LastUpdatedBy was a client as opposed to one of our support
staff.

What would the correct TicketSQL be to get something like:

(Status = 'open' OR Status = 'new' ) AND (  Owner = '__CurrentUser__' ) AND
(
  LastUpdatedBy IS AN UNPRIVILEGED USER
  OR
  LastUpdatedBy.User.Email Not like '@ourdomain.com'
)

Is such a query possible in TicketSQL?

I searched the web and could only find an announcement of release
3.6.7 where one of the change notes was:

    "* add id to the list of users' properties you can search by [ruz]"

but I don't know how one actually searches on a user's property in the
QueryBuilder.