5. iOS Outlook
6. MacOS Outlook
I think they're all heading in a direction to use the web-app as the core.
iOS Outlook is surprisingly good, though. Much better than gmail's and protonmail's ios clients.
> The latter is actually pretty good - been using it for a couple of months
You must be using a different New Outlook than me. I've been conscripted into trying it before the mass rollout to the rest of my company. It's so slow and missing so many features from the Old Outlook that it's only really usable for the most basic tasks.
1. Outlook desktop - old MFC / win32 crapfest
2. Windows Mail / Calendar - new WPF crapfest.
3. O365 online outlook / outlook.com - fat web app.
4. "New" Outlook - this is a fat Electron style app based on the web app.
The latter is actually pretty good - been using it for a couple of months. This is apparently going to replace all the other ones on the desktop.