Outlook 2016 shared mailboxes not updating
More likely is that you are have been granted “Full Access” permissions on the mailbox by your Exchange administrator.In that case, the additional mailbox is being added automatically via the “Auto-Mapping” feature of Exchange.If you are the “owner” of a Shared Mailbox account, your best solution is to turn off “Download shared folders,” as explained above or upgrade to Outlook 2016.Check out this knowledge base article I found in the West Virginia University knowledge base.
The impact on the offline cache file depends on the following: The simplest solution is to turn off "Download shared folders" using the steps below.
It also allows you to set some permissions which can’t be set by any other way.
The following permissions can be set on the folders; Note that you are only setting permissions on the folders that are listed and on not their subfolders.
If you do this you must make sure that you have at least Folder Visible permissions on that folder and on the one above to make travelling to that folder possible.
If you don’t do this you won’t be able to expand the folders.