Before restoring a user's account, ensure the backup file is in the correct location on the server. By default, the path to a user’s account is C:\SmarterMail\Domains\domain.com\Users\username. Delete the user from within the web interface. Place the user's backup Mail folder back in place. Then, follow these steps to restore the user's entire mailbox:
 
Log in to SmarterMail as a System Administrator.
Click on the Manage icon.
In the Domains section, click the Actions (...) menu to display your options and select Attach User.
A modal will open.
In the Email field, enter the full email address of the user that will be restored.
Click Restore.