On our Exchange Unplugged Tour - I've had lots of questions from customers about what they have to do to get Push Email with Windows Mobile 5 devices.
I have to re-iterate that you need two components:
1) Exchange 2003 Service Pack 2
2) Windows Mobile 5 devices that have AKU 2.0 integrated - all new devices from Q1 next year will have this integrated however existing Windows Mobile 5 devices will need an upgrade - you need to check with your OEM/Operator on when they will have an upgrade.
From an infrastructure perspective you have to deploy Exchange Server Activesync - there is a great document on our website that describes step-by-step how to do this -
Once you have that in place then all you have to do is:
1) Upgrade your Front End Server to Exchange 2003 Service Pack 2 - you do NOT need to upgrade all the Back-end servers.
2) You then need to extend your ISA or other Firewall timeout from it's default of 120 seconds to 1800 seconds (30 minutes) - the reason for this is that the Push Model needs the SSL connection to stay open (but not using data) for >15 minutes to support the Push Model.
Many customers are about to hit change freeze for the Christmas period so if you want to take advantage of this in the future it's important to make those changes ready for when the flood of devices appears early next year!