If you cannot search for messages in Apple Mail (a search doesn't find expected results), try rebuilding the Spotlight search index for email messages.
Go to Apple menu, then "System Settings" On newer operating systems, click "Spotlight". On older (pre-Sonoma), click "Siri & Spotlight". On older systems, scroll down to search results on the right. Deselect "Mail & Messages." Wait for a few seconds. Restart your Mac. Repeat all the steps, but reselect the "Mail & Messages" option. The search for Mail should be rebuilt.
Note 1: The restart might not be necessary, but include it if you can. Note 2: After these steps it might take a while for the search to be fully rebuilt.
I usually write a blog post about once a week. The latest post can be viewed here: Terrorism vs Genocide: Please don't feel like you need to be ashamed of New Zealand's response. (posted 2025-10-03 at 17:02:25). I do podcasts too!. You can listen to my latest podcast, here: OJB's Podcast 2025-09-09 Kiwi Values: From a practical perspective it has too many problems..