All my invoices are delivering without any problem except for one invoice. It to was delivering without any problems and was also being viewed by the other party until today. Every time I try to resend a reminder it comes back at delivery issue. It is only this invoice that is doing it. I think possibly the person receiving this has blocked us. Is this what has happened. See attachment, the attachment shows that the customer was receiving them and viewing them, and now there is a delivery issue error.