Redback has an importer for marking orders as dispatched and sending email notifications to customers;
to use this feature, you first have to create a csv file (there is a template attached to this guide)
in column A, add the order ID from redback
in column B, add the tracking code form your shipping company
if you dont have a tracking code, then leave column B empty
goto your redback admin area, and in the links at the bottom of the admin dashboard, there is a link for 'import tracking codes'
if you click that link, a page opens with instructions on the format of the file and an upload button.
simply upload your file and it will process and close the orders, sending a dispatch email for each.