Every invoice also as an e-invoice to Peppol BIS 3.0.
Works today and has been tested against the real service or the real file format.
On every final invoice. Sending over the Peppol network itself is a separate integration: see Peppol.
For every invoice Trajenda creates a UBL file that any accounting package with e-invoice import can read. It goes along as an attachment with the invoice email and is a download on the invoice. If a required field is missing, you get no half file but a list of what is missing.