Use resource accounts instead of full-fledged accounts. Mail is still
delivered as per-normal, but it doesn't use up licenses. These are
shared resources, after all, and not e-mail accounts.
Shoot! Any way to transform a regular account into a resource account?
Yes. :( This, and the lack of tags on shared folders, is a real
downer for using Zimbra in collaborative environments. This is
supposed to be fixed in Zimbra 7 (or is it slated for 8?). There's a
couple of bugs about this, with lots of action recently.
I'm quite certain it'll not be resolved with Zimbra 7. There was hint of a collaboration environment for 7 at one point, but I got the impression that it'll either be part of 8, or an (additional cost?!) add-on. If it were an additional-cost add-on, that would royally suck. But we'll just have to see what happens.