Apache 2, Webmail
Apache 2 allows "ProxyPreserveHost" option, which ensures that the website requested by the client is passed to the proxied machine - that way Outlook Web Access knows how to insert correct URL's into the returning data. Works ver nicely now.
I must say I'm very impressed with the modular way Apache 2's configuration works. Heaps neater than one monolithic file, especially if you have multiple sites of configs.