HOW TO: Restore mailbox data without restarting smartermail service.
1. Restore the user's .grp files to a temporary location, if you accidentially restore the mailbox.cfg file delete it.
2. Browse to the user's live mailbox directory, it will be something like d:\smartermail\domains\example.com\users\bob\
3. Switch to the Mail directory
4. Create a new folder, for example Restore. Copy the restored .grp files to this directory.
5. Logon to the user's mailbox via webmail (you can use the impersonate function)
6. Create a new folder in the root, call it Restore
That's it! Upon creation smartermail recreates the mailbox.cfg file, allowing you to access the mail data. Drag and drop the emails via webmail back to their correct location. After completing this delete Restore via webmail.
The process is not disimilar to the official process (http://portal.smartertools.com/KB/a1472/restore-a-mailbox.aspx) but it differs in as much as we pre-create/populate the directory on the drive then create within smartermail and critically there is no need to restart the service.
This was tested with 8.x but I suspect it will work with earlier versions.