The add-in handles printing the emails and the attachments in order.
Similar to when they are printed automatically as they arrive, to print an entire folder follow these instructions: How to batch print emails and attachments in a folder:
Also, you can control which pages get printed, how many copies to print, or which types of attachments get printed (for instance, just PDF files). Note that with the add-in, you can select the Sent Items folder as well, which effectively prints sent emails (which has the advantage that you can print the email header information).
To print a single email, follow these instructions: How to print email in Outlook: If you continue reading, we’ll also tell you how to print an email attachment. In Outlook there are two ways to do this, depending on if you want to print a single email or a group of emails. Printing emails is important when you need a hard copy.