Where are you looking Greg?
In 2016 the inboxes are listed by default in the "Favorites" (sic) panel. The folders for each mail account are listed underneath the "Favorites, grouped by account name, you need to click on the arrow to the left of the name to expand that list.
If you can't see the Favorites panel, it may have become minimized (sic). It is to the left of the Outlook application; a right-gabd arrow exoands it, left-hand minimises and the drawing pin will 'pin' it open.
Sorry, I am my phone and do nit gave access to my laptop for screenshots. I hope that helped and did not confuse you further
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