iOS-like standalone, lightweight app
I would happily pay €10-20 for a lightweight, standalone Outlook Mac app, similar to the apps on iOS.
Standard Outlook is super heavy, clunky and has about a million features I never use. The iOS app has been a revelation and I would love to see something similar on the Mac.
Ideally this would come free to 365 subscribers, but even as a subscriber I think I'd happily pay for a really good, clean app.