using:
zcs-NETWORK-5.0.2_GA_1975.UBUNTU6.20080130232321
on Kubuntu/Ubuntu 7.04 (feisty - unsupported)

When I try to share a briefcase, the web interface works as expected (very nice, intuitive) and sends out the email to the user but when that user tries to access the briefcase with the supplied URL:

http://host.subnet.uuu.edu/home/user1/shared

it fails with:

HTTP ERROR: 501

can only handle messages/appointments/tasks/documents

RequestURI=/service/home/user1/shared

The maillog doesn't say anything about this and I can't find any other log that explains this.

I did find this:
<http://bugzilla.zimbra.com/show_bug.cgi?id=22561>

but it seems to refer to another kind of bug.

In addition to my previously noted briefcase bug at the forum,

this is another situation where /briefcases/ appear to work correctly on the interactive web user interface but fail during actual sharing.

On the other hand, it looks like sharing notebooks works perfectly.