In the course of a business sale, I sometimes use the 'Request Money' tab and 'Create an Invoice'.
When the invoice is paid, I get an email, whose heading includes the invoice number. So far, so good.
I'm using PayPal's IPN with my back-office database, but the notification IPN includes no invoice number. It seems there's no way I can automatically associate the payment with the Request I sent out.
Does anybody know how I can get my invoice number into the Instant Payments Notification?
