I made the new user a manager for the old user's inbox. The link I use to go to the shared Inbox is:
https://servername.com/home/
username@
domainname.com/Inbox
I tried to share the Inbox, but get the following error when we try to follow the link given:
HTTP ERROR: 501
can only handle messages/appointments/tasks/documents
RequestURI=/service/home/
username@
domainname.com/Inbox