I was tryin to be funny ... because of course they are gonna use outlook since it's their own product from their own inventory
the Search feature in outlook is garbage compared to Lotus Notes search. Otherwise, I can't really complain too much about it.
That search issue is probably due to Exchange - honestly I don't use Outlook much with accounts that delivered via Exchange so it could just be the client, but I can tell you I've had variable success with Outlook searches. I've witnessed the search-related issues on Exchange servers themselves, and I personally haven't figured out what voodoo must be done to fix it more often than not. I do know when it is working correctly versus when it's broken, as this can be with the same query before and after someone fixed search on the server.
And yes, even though you generally have emails stored locally, the search function performed on Exchange accounts relies heavily on server queries. I think the "All Outlook Items" selection in Outlook search will query local files.
Suffice it to say though, that Microsoft has rarely been considered an expert in search features. Searching on Windows can be appalling, and then of course they have found ways to make it incredibly variable with the Windows 10 start menu searching and they somehow break it from time to time.