Re-instate the "Group similar folders, such as Inboxes, from different accounts" preference that was removed in July 2017 Update of Office
In the July 2017 update of Office 2016, you removed the item:
Preferences \ Personal \ General \ Folder List \ Group similar folders, such as Inboxes, from different accounts.
Now we have mailboxes organized like:
What we had before was the option to have:
\Office365account1 (which shows the inbox for that account
\Office365account2 (which shows the inbox for that account
\SomeIMAPaccount1 (which shows the inbox for that account.
Here is the official Outlook for 2016 documentation which shows how to turn this feature on and off.
Here is a non-microsoft help link, which explains the feature in more details.
The fact that you have removed it completely is terrible. We have hundreds of users that use the grouped inbox feature like Apple's Mail app.
PLEASE PUT IT BACK.