The "Active Destination Objects in Memory" figure represents destination objects/locations that the IronPort is delivering to.
So if it is delivering to 20,000 locations, there are 20,000 objects in memory. (If you use virtual gateways, that number will be higher.)
Every time the IronPort receives a new destination. the number goes up.
How many of these items you have depends primarily on your mail volume, and how quickly recipients are accepting connections. Many high-volume recipient domains throttle incoming connections, so it is not unusual at all to see at least some items in the Active Destination listing.
