How would you create a heartbeat monitor for all servers including new ones, but exclude one or two.

Monitor > Alert rules

   Whenever the total heartbeat is less than X

      Split by Dimension

             Computer = All current and future values

             can't add the same dimension

              Computer !=  ServerInMaintenance

Tried setting custom computer names, but there are to many to be displayed to check.

Open to any better way.

Just need an email alert when any server is down for more than 15 minutes and ability to temp exclude.