If you prefer not to send the invoice via email but want to send it by post, for example, that is also possible.
Select the relevant invoice and then click on "Send."
Where the recipient's email address is filled in, you have access to a drop-down menu. There, you have the option to "Mark as sent."
After "sending" the invoice, it will be assigned an invoice number, even though the invoice has not actually been sent.
You can now download the invoice with the invoice number.