You recently experienced a power outage as a result of which you lost user data.
If you are running Kerio Connect on macOS, please follow the steps within our Kerio Connect Not Showing Data in User Accounts After an Unexpected Reboot/Shutdown of the MacOS Server
Otherwise, if running Kerio Connect on a different OS:
- Check if the user's Inbox folder is gone or not from the Kerio Store folder > mail > Your Domain > Affected User.
- If the user folder is there along with their email, Reindex the affected user.
- If the user folders are gone or empty, you can Manually restore lost or corrupt user files and folders from backups