This is especially helpful for printing hard copies of the sales order, which you may need to mail physically to the customer or to file in your own records.
In the Sales Order’s top right bar, click on either Print or Preview Sales Order button.

Clicking the Print button would prompt you to download a PDF, which you can view in a PDF reader and print. If you click 'Preview', you will be taken to our new document viewer, like this:

Clicking on 'Print' takes you to this page, where you can do final checks and print your sales order.
