RPC over HTTP is mainly used to allow Outlook clients, outside of the network, to connect to the Exchange Server without the need for a VPN.
Here is a good site which contains the requirements for Exchange 2003:
http://www.amset.info/exchange/rpc-http-tips.aspIf you are using Exchange 2007, RPC over HTTP was renamed to Outlook Anywhere.
The requirements for Outlook Anywhere are mostly the same, except it will also work with Outlook 2007, and there is a little less setup on the server side.
The biggest item needed on the requirements list is a proper certificate, not a self-signed certificate.
I found the best type of certificate for this purpose is an UCC certificate.
A UCC certificate allows for multiple domains to be set to the same certificate (great for Exchange).
I recommend this site for certificates, I have not had any problem with them, and they're relatively inexpensive:
https://domainsforexchange.net/
