These under-the-hood changes aren't complete and neither are the new features they'll support. While its appearance is pretty much a facelift, it has a lot of under-the-hood changes such as server-side searching for Office 365 accounts and greatly reduced data footprint where it won't download/cache the entire message store (think 30 GB reduced to 400 MB). The 'New Outlook' is a preview not a final product.

Microsoft Office is the worst malware to ever infect a Mac 🤬 If Apple pulled this crap with their software, offering a 'new' version for months and months and months with no clear strategy for release I would be just as PO'd. This proves yet again what I have said for years. Apple got Microsoft into the application software business back in the early 80s. Outlook often has caching issues, and fails to sync emails, contacts, and events with the server, which results in this data not syncing to mobile devices. Outlook for Mac has always been missing important features that the Windows version has, like the ability to export to PST and easily reopen the PST files for viewing later. Apple users are charged the same amount for Office but they get less product in return. Really? Shared mailboxes are not supported by this “new” and allegedly improved Outlook? I have no idea what they’re thinking in Redmond. When I switched to it just now, I was told that a shared mailbox that I had attached to the account that is logged in is not supported. Switching to the “new” (incomplete) Outlook will not give users anything new, except a reskinned interface that looks like macOS Big Sur. They have been blogging about this software for months, and extolling the great new features and better performance. This new version is still not feature complete. I’m disappointed that Microsoft still has not released their so-called “new” Outlook for Mac users that promises better performance and better features. Microsoft released version 16.45 of their Office apps for Mac yesterday.

Outlook for mac current version