A customer has recently placed an order and not supplied an email address during checkout.
They have now send me an message with their email address requesting an invoice for their order.
I have added their email address to the order details, but I can't see anything that will allow me to issue an invoice.
How do I issue an invoice for an existing order? Surely I'm overlooking something simple??
You've probably found a solution since then, but I just wanted to contribute for future reference.
There are many ways to generate an invoice. Shopify provides a default packing slip to print, with a somehow OK invoice. You can find it directly in the order page, and then once the order is marked as fulfilled, an option "print packing slip" will be available, generating the pdf.
There are plenty other Apps existing to basically print invoices, which you can find on the shopify App Store.
We're using personal print for our invoices because it lets us smartly customize our invoices, and they can then be downloaded directly from the Shopify orders' list page.