How BES gets email to your handheld

Going through plenty of BES logs lately, I have noticed a pattern that I am going to try to explain briefly. It seems that people don't understand why it is a bad idea that a large percentage of your messages are being delivered via rescan, and not by notification. I am going to try to explain this in more detail.

• Notification- This is when the BES See's that a new message has gone into your mailbox, it then sends the message to your handheld through the rim infrastructure and you get it on your handheld.
• ReScan- This is when BES does a rescan of the users mailbox every 15 minutes or so, and then notices that a message has not been marked sent to the handheld, and then is sent to the handheld.

Now obviously, the notification should be the one that always happens, but with the exchange environment getting overloaded, sometimes things need to get picked up with the rescan. Now the problem we get into, is when companies start to depend on the rescan. Then you start seeing things like mail clumping and latency issues. There is a BRK that you can run that can assist you with this information is messageflow. The general accepted rule is that your rescan % should not be more then, at the very worst of 20%, I would even say 15%. So no more then 20% of the total messages sent to your BlackBerry should be delivered via rescan