DE-R-007
A Peppol Germany national rule (DE-R-*) – applies when the invoice is sent over the Peppol network to a receiver in Germany.
What this error means
DE-R-007
When both seller and buyer are located in Germany, the seller contact e-mail (BT-43) must be provided.
How to fix it
Fill in cbc:ElectronicMail in the seller cac:Contact block.