Du findest im Benutzerkonto unter dem Menüpunkt Rechnungen alle offenen und bezahlten Rechnungen, bei denen du die Zahlungsoption Rechnung ausgewählt hast.
You can find all open and paid invoices in your user account under the menu item Invoices, where you have selected the payment option Invoice.
Under «Orders», in the detailed view of the respective order, you will find all associated documents such as the invoice as a PDF, which you can download or print out there. For ecological reasons, no paper receipt is enclosed with the parcel or envelope.