Like I've said before, THE killer app of Exchange/Outlook 2003 is RPC over HTTP. But what exactly is it?
Some of the Microsoft people have been blogging about it. Over on his blog
, Steve Lamb talks about a post by Eileen Brown where she explains pretty much exactly what RPC over HTTP is.
Eileen also gives a bit of info on the OSI networking model to boot on her post. Good stuff.
I'd explain RPC over HTTP as a secure way of leveraging the HTTP connectivity built into the Outlook Web Access (OWA) part of Exchange to connect directly to the server using Outlook without using a VPN.
Basically, if your organization already allows use of OWA, they do not need to open up any more ports on the firewall to do RPC over HTTP.
In other words, if you are already using OWA, RPC over HTTP gives you the same connectivity between the full Outlook client and the Exchange server that you would get if you were connected to your company's network directly, but you don't need any other special software and there is little, if any, further risk to the network.
Other people can talk about IMAP and other similar technologies, but in my mind they don't really rival what you get with Exchange, Outlook and RPC over HTTP.
What do you feel are some other "killer apps" for Exchange 2003. Other than keeping up with the migration path, why did you purchase Exchange 2003?