My small company (7'ish people) have been using Goldmine CRM for about 3 years now. It's kind of a love/hate relationship, but there's one single feature that we love about it - its ability to auto-group incoming email by the recipient / company from whom the email came.
For example, let's say that 3 of us in our company are, individually and over time, having a conversation with a single person in a another via multiple emails. If I go to the 'History' tab in Goldmine for that person, then I can see, in a single list, ALL the emails to and from that person over time from all of us. Great for reviewing who said/promised what and when.
Before Goldmine, when we were using Outlook, we had to create shared folders (e.g. one per company), and then have to individually remember to drag emails we received into that appropriate shared folder. Not very satisfactory or reliable!
How well does Zimbra do this?
p.s. My first post at Zimbra forums - not sure if I've chosen the best section to ask this question (in the absence of a 'pre-sales' section).