For some of our users, but one in particular, searching in Outlook for Mac O365, version 16.23, gives incomplete results. This user has had this problem for over a year. We tried the Index repair tool for Mac, tried to re-index by removing and re-adding the folder to Spotlight, but nothing really helped. Most emails come up in the search results, but some remain missing. Moving a specific email to another folder and back to the inbox again, will make this email appear in search results, but this does not solve the problem as it is not clear why only some emails are not indexed.
Because of this issue, his laptop was re-installed a few weeks ago, so his search index is brand new, but he still has the same search problems. For example, searching a contact name gives most of the emails received from this contact, but an email received a few days ago is not included in the search results. Why???
I checked OWA, and the search problem does not exist there.
I have tried all suggestions I found in my online research, but this does not solve the incomplete search results (most emails are found, some are not).
This user keeps al of his email in his inbox, which makes the folder huge. When he first reported the problems, his inbox was about 6 GB in size and is currently 13 GB. Could this be related?