Using Classic Outlook on Windows for personal email, calendar, and contact management
Yes. If the account is Exchange, Outlook.com, or IMAP and the older mail still exists on the server, older messages should be visible in Outlook on the web. If they are not visible there either, the issue is not just the local .ost cache.
For the .ost error specifically:
- Close Outlook.
- Go to
%localappdata%\Microsoft\Outlook. - Find the
.ostfile that reported errors. - Delete that
.ostfile. - Start Outlook and let it download the mailbox again from the server.
This is the recommended resolution for corrupted .ost files in Outlook 2013 and later. Scanost.exe is no longer used in Outlook 2010 and later, and if Scanpst.exe does not successfully repair the .ost, the supported next step is to rebuild the .ost by deleting it and letting Outlook recreate it.
Important: if there is any local data that is not on the server, export that data to a .pst before deleting the .ost, then after Outlook downloads the server data again, import the .pst by using Do not import duplicates.
If the problem is specifically that Outlook search cannot find older mail in classic Outlook, also check the local sync window:
- Open classic Outlook.
- Select File > Account Settings > Account Settings.
- On the Email tab, select the account and select Change.
- Move Download email for the past: to a longer period or All.
- Select Next and Done, then restart Outlook.
That setting affects what is cached locally for indexing. It does not explain older mail missing from Outlook on the web.
References: