The last time I tried Zimbra I was not too happy to see it installed its own versions of services like MySQL and Postfix. I started a thread on the Zimbra forum back then and it sparked a bit of debate. Unfortunately Zimbra 3.0 still assumes the install system is only going to be running Zimbra which makes it difficult to install on a system already running most of these services. Although I specified different ports to avoid conflicts my test install did not work at all very well and to top it off it managed to break the existing OpenLDAP installation (something to do with missing shared libraries).
Even though things did not work straight off the bat the Zimbra feature overview movie and the little that I had been able to experience had me hooked. Rather than fight the Zimbra install process I decided to setup Xen on the server and provide Zimbra with a clean virtual server to install on. After an evening of toil I finally had my virtual server running fine so I ran the Zimbra installer. Everything installed and ran without issue using the default options and the speed was acceptable given the hardware was now running two instances of Linux, two mail servers and a host of other services. Migrating mail from Hula to Zimbra was problematic as automatic tools such as imapsync do not play nicely with Hula's implementation of IMAP. I eventually resorted to using Thunderbird to copy mail from one server to the other which resulted in the loss of 'Date Received' data. Once the mail was migrated I replicated Hula's mail proxy functionality with fetchmail and switched from a testing to development system without any downtime.
Setting up webmail proxying with Apache was fairly straightforward but it did require a change of the default url for the spellchecker. I posted a question about how to do this on the forum and it was solved within the day. For future reference to change the default spellchecker url use the following command:
/opt/zimbra/bin/zmprov ms SERVERNAME zimbraSpellCheckURL SPELLCHECKER_URL
and then restart Tomcat (or just restart Zimbra).
Like many others I would like to see the Outlook Connector sold as a separate product (with single and pack licenses) so that users of the open source version can get the functionality of Outlook without having to pay for the Enterprise edition. Support for me is not an issue and most of the target install sites I know of are too small to really justify the price of the Enterprise edition (but nearly all use Outlook). I am also holding out for the Zimbra iSync adapter and hoping that this to does not just get bundled into the Enterprise version. It is something I would pay for especially if it lets me add/edit contacts and calendars in OSX and have them synchronised to Zimbra. This would be especially useful to keep all my contacts/calendars in sync across the three Macs I now have (something that .Mac can do but I don't want to pay $200 a year for).
Whilst the web interface is great I prefer native applications because they are (and will always be) much faster and enable offline work to take place. Plus the main reason I use iCal is to easily set alarms in my cellphone so if Zimbra and iCal could work together I can keep my phone reminding me.