ZyXEL Communications ZyWALL USG Series Application Notes page 186

Click Configuration > AppPatrol > Query, and in the second dropdown menu,
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select Instant
Messager, and click Search. Then, double-click the msn entry to edit it.
Click the Add icon in the policy list. In the new policy , select WorkHours as the
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schedule and Sales as the user group that is allowed to use MSN at the appointed
schedule. Then select forward in the Access field. Click OK to finish the
setup.
Now only the sales group may use MSN during work hours on week days.
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