I found this old thread while searching for "GroupWise." Refreshing because I could imagine this being useful to people, and it took a lot of time for us to find this.
The beta GroupWise migration utility is documented at:
http://www.zimbra.com/docs/ne/latest...llation_guide/
There are several open issues in bugzilla, the most significant probably being RTF/HTML attachments being migrated as Text.htm attachments rather than multipart/alternative, and calendar item time zone information being lost (it always to the migrating machine's time zone).
Both of the above issues appear to be handled by manual imapsync or iCal export/import work, but that's *a lot* more work. Only the GW migration utility appears to handle addressbooks well. Neither .NAB (CSV) not vCard do entirely the right thing with the hierarchical "Organization" addressbooks supported in GW.
Unresolved issue for us: How to migrate "Archived" mail. GroupWise has "Archive mail older than N days" functionality similar to Outlook, where older mail is removed from the server and stored exclusively on the client, in proprietary GroupWise format. We have people who have been using various versions of GroupWise for more than 10 years with very significant amounts of locally stored mail that we'd like to keep.
As for iCalendar/iTIP meeting request coexistence: GroupWise, even version 7.0.1, cannot handle recurring events. When GroupWise receives or imports a properly formatted vCal/iCal event with recurrence, only the first instance is seen. The rest are silently lost. This is a general problem with GroupWise that also affects interoperability with Novell's own Evolution client.