Since the integration of Peppol with Odoo in v17, many changes have occurred between versions. In v18, it is no longer possible to set default sending preferences. For your European B2B clients, the sending preference is set directly in Peppol due to legal requirements. In this video, you will find a workaround to set a double default preference, via Peppol and by Email, as the new version 19 currently does.