We have been using WMI counters to monitor our Exchange server and have noticed a recent increase in the number of user connections on the Exchange store. I know that ActiveSync, Outlook, OWA, and some 3rd party applications add to the number of active conenctions. Is there an increased number of connections generated when running Outlook 2007 in comparison to Outlook 2003? What I am trying to understand is how I can estimate the expected number of connections based on the applications and number of users we have so that we can adjust our monitoring thresholds. I have reviewed a few articles, but the best information I can find is the 32 MAPI connection limit per user.

Not sure if this helps but we recently had to increase our MAPI session counts to 128 per user. We use Outlook 2003, Exchange 2003sp2, Blackberry, Windows Desktop Search, X1 (another desktop/email search tool), etc. The search tools really hammer the Exchange servers especially if indexing is turned on. We're still evaluating whether or not 128 MAPI session count is going to cause other issues on the server. But the folks I work for just want it to work but not necessarily correctly... (same old story).