There are sound, functional reasons against the adoption of the new Outlook:
- It cannot access on-perm mail servers because it's not a real email client. Rather, it's a glorified PWA.
- It's not economically justifiable because it doubles our email storage cost. Previously, owning a premium Gmail account mean we had to pay Gmail for the extra storage space. Now, we have to pay Microsoft too because the New Outlook transfers our email to Microsoft Cloud and charges us for the space they consume.
- It's a security liability because, as I said above, the new Outlook stores a copy of our Gmail message on Microsoft Cloud, thus make Microsoft a middleman.
To sum it up, the question is, "Suppose I adopted the new Outlook. What's in it for me?" The answer is, "more trouble, higher expenditure, higher TCO, lower security, and vendor lock-in."
Microsoft