After a post office is upgraded to version 18, users can run the GroupWise 18 client on workstations that meet the requirements listed in GroupWise User Requirements. If necessary, they can also continue to run their older GroupWise clients. However, older clients do not have GroupWise 18 functionality just because they are accessing mailboxes in a GroupWise 18 post office.
IMPORTANT:A user who needs to proxy into another user’s mailbox should not upgrade to the GroupWise 18 client until the mailbox owner’s post office has been upgraded to version 18. The GroupWise 18 client cannot proxy into a mailbox that has not been upgraded to GroupWise 18.