To start, I will say I love and miss Outlook. One thing that chafes is the lack of a unified inbox.
I have used it for many years but have moved on to a small third party email client that supports unified inbox, at the expense of many things Outlook does well. I had it when I was a mac guy, but as a ,net/SQL server developer I live 99% in the windows ecosystem. I watch jealously as the Mac version of outlook gets update after update and becomes a much better product. Why, oh why can't we have the same universal inbox on the MS Flagship program for Office? Is MS telling us that its not good to have multiple email accounts? Are they telling me to get another Mac? Any news on the horizon for this?
So 2 years later and no response. Outlook did have a unified inbox 10+ years ago, but they took it out after just a few years. It was for POP only, as I recall. But now, even the toy mail program that comes free with Windows offers a unified inbox and fee-paid Outlook doesn't. It makes Outlook an unsuitable product for the individual user. Let's wait and see how many more years go by with no answer to this question.