ERROR: "You have already installed this shared folder"

ERROR: " You have already installed this Shared Folder"
Cannot accept two different Shared Mailbox folder

This feature has been turned off in GroupWise backend as it was costing a lot of performance problems.  The option was left in the Client UI, in case development wants to revisit it to make improvements in this area.  If sharing the mailbox is a desired feature for users, please open up a Enhancement Request with GroupWise development, preferably via a Service Request and include information about the impact to the users.

Workaround:

Instead of sharing the entire Mailbox folder, give proxy rights to users who needs access to Mailbox.

OR

1. Login as user who needs to share their mailbox, create a new folder anywhere in Mailbox or Cabinet.
2. Click on Tools | rules and create a new rule such a way that it will move all incoming mail, appointment, task, reminder note  etc to the new created folder in step 2.
3. Now share this new folder with users who needs the access to the mailbox

Novell originally left the mailbox out of sharing, then temporarily included it because Outlook supported it.  Soon after this was found to cause very serious performance problems.  This means that the folder will share and you will see the items in the
folder at the time of the share, but new items are never replicated as they are delivered.

It's possible that performance could have been improved over time, but since then Novell has dropped support for Outlook and Novell found that almost no one used this feature anyways.  The option was not diabled in the UI in case Novell had to go back and make improvements to this area.