It looks to me like your primary question is whether or not you can fork parts of Zimbra.
The answer is nope. Zimbra comes with its own mysql, apache, lucene, postfix, etc. All of these components are specifically engineered/configured for the Zimbra Collaboration Suite.
There has been some discussion in the forums about installing zimbra on to existing postfix/mysql installation, although I'm not sure it's really gotten anywhere.
This is a collaboration suite, and not really a "full groupwhere" solution quite yet. What I mean by that, is that you don't login and get a "home page" with 5 messages in your inbox, company news, etc.
E-mail, notebook, calandaring, and in the future possibly chat. |