Outlook online (I have M365 business basic) search sucks just as much. It finds really recent emails and ones from years ago but nothing in between for some reason.

The desktop outlook (the real one, not the 'new' one which is just the web version) is much better of course as it searches locally but it's only on windows. And thunderbird doesn't work great with M365.

But anyway my point is even supposedly premium services screw this up.

>> The desktop outlook (the real one, not the 'new' one which is just the web version) is much better of course as it searches locally but it's only on windows.

I am very confused by the MicroSoft product branding, but on MacOS there is a "proper" application: "Microsoft Outlook for Mac". As I understand this is called the "New Outlook" which is a native, non-Electron version. As it is not Electron based it is only 2.6GB (/s).

Anyways.. the search capabilities are insanely bad for searches outside of your current mailbox. It might be related to handling of large result sets where it just provides a limited set of random hits as opposed to a set with the most recent hits. When you provide from-to dates (from a hideously complicated "advanced" menu) the results seem a bit better.

edit/addition: on MacOS, Outlook supposedly uses the native "Spotlight" search engine. MacOS spotlight, when used from the Finder, actually does a really good job in finding the E-mail .eml files from the file system and, when clicked, they open up in Outlook.