User was migrated from Exchange 2010 to Exchange 2016. When the user searches for mail in Outlook or OWA, only results for mail that was sent/received after the migration date is returned. All of the mail was successfully migrated, and you can browse to it and view it manually, it just doesn't show up in search.
Setup is four Ex2016 servers, consisting of two DAGs with two servers in each.
Known User Scope
- Affecting multiple users across different databases on the same server.
- Some users on a different server are not affected.
- Affected user has issue regardless of which server the database is active on.
Unknowns
- Whether all users on this server are affected.
- Whether any users on other servers are affected.
I have stopped the Search services on the server, deleted the {guid} index folder in the edb path, started the services, and then waited for the index to be rebuilt and reported as healthy. After these steps, the issue still persists.
Could you find these emails that was sent/received before the migration date if you run the command Search-Mailbox?
If the command doesn't return these emails, I guess that the migrations of mailboxes were not completed or encountered some problems. To regain these emails, one my suggestion is that you could export full emails from the problematic mailboxes to .pst files(If available) and then import the .pst files to the current locations.
At the same time, here is an official documentation about the content Index and search in Exchange 2016 for your reference: Exchange 2016: Content Index and search, based on its description, you could check if the service "Microsoft Exchange Search" is running, if there were some errors in the Event Viewer after you performed a search, and check if the content index status of databases is healthy by running the following command: