The anatomy of a signature policy - exceptions

Exceptions are used to specify any exceptions to conditions which have been set. For example, if you have defined a condition to match everyone within a given department, you might then define an exception to exclude individual people within that department. Use the exceptions tab to set required criteria:   

Once an exception is selected, any options for that exception are displayed as hyperlinks in the lower pane - select these links to set / refine criteria for the associated exception.