monterey problems with mail

tauhammerhead wrote:

Just installed Monterey and my mail is behaving oddly. Most flags have gone and search does not work properly. When searching I only get examples from 2013!

You can Rebuild the Spotlight index on your Mac - Apple Support

for isolated mailbox issues—Rebuild mailboxes in Mail on Mac - Apple Support

Additionally, give this a try: boot into Safe Mode according to How to use safe mode on your Mac and test to see if the problem persists. Reboot normally and test again.