I just discovered Zimbra and am absolutely in awe - what a fantastic product!
I have show it to a client of ours who is equally impressed but there is (of course) a wrinkle.
They currently use a combination of Thunderbird, sendmail, dovecot, and some clever mail filtering. Whenever they press the "send" button in Thunderbird, a purpose written plugin pops up a dialog box and asks them for a (for want of a better description) a customer number. They either enter a customer code or they enter their own "private" code. This gets emebedded in a X-Header within the email.
When the email is sent, a mimedefang filter (written by us) grabs the email, looks at the header that has been inserted by the plugin and "files" a copy of the email in the "customer's" folder (or in their own copy-to folder).
This sounds very complicated, but is used to ensure that all correspondence (for legal purposes) is "filed" and recorded. This info is also used for charging purposes.
Any ideas if we could somehow recreate this behaviour using Zimbra? If we can solve this we have a total convert.