After a post office is upgraded, users can run the GroupWise 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 the latest GroupWise functionality just because they are accessing mailboxes in a an upgraded GroupWise post office.
IMPORTANT:A user who needs to proxy into another user’s mailbox should not upgrade the GroupWise client until the mailbox owner’s post office has been upgraded to the latest version. An upgraded GroupWise client cannot proxy into a mailbox that has not been upgraded.