I updated my work Mac to version 27 late last week. I've used Apple Mail for about 20 years because it's simple and its search has always been fast and useful, especially when looking up exact strings such as UPC codes or product numbers.
Since the update, searches seem far too approximate. For example, searching for a five-digit code containing "067" may return messages with "061" or unrelated seven-digit numbers. I'm getting dozens of emails that only vaguely resemble the search term and don't actually contain the exact text.
Is there a setting to disable this kind of fuzzy matching, or is there a way to repair or rebuild Mail's search index?
2 Answers
It may also be a regression in the new version rather than a setting you changed. Exact searches for codes and product numbers are especially sensitive to fuzzy matching, so if reindexing doesn’t resolve it, installing the next maintenance update or temporarily using another mail search method may be the practical workaround.
The update may have triggered a Spotlight reindex. Mail relies on that index for searching, and results can be incomplete or inaccurate while the process is running. Check whether indexing is still in progress and give it time to finish; if it appears stuck, rebuilding the relevant Spotlight index may help.
That could explain it. I’ll check the indexing status and either wait a little longer or rebuild the index. It just seems unusually slow since it has already been several days.

That’s what I’m worried about. I’ll let the reindexing finish first, then look for a maintenance update if the results are still this unreliable.