3714108 - eInvoice Germany error: "Email 'Billing document XXXXXXXXXX' could not be sent" on action Send to Customer in Manage Electronic Document app

During the attempt to send the invoice to the customer, the system raises the error “Email ‘Billing document XXXXXXXXXX’ could not be sent” in the Manage Electronic Documents app.

• SAP S/4HANA Cloud Public Edition
• SAP Document and Reporting Compliance, Cloud Edition

XML file, E - Mail, Sender Address, Manage Electronic Document App, Email Allowed List, Sender Domain, Germany, eDocument Cockpit, DRC, eInvoice, EDOC_COCKPIT, Send to Customer, Billing document, 101313, Define Allowed Email Sender Domains for email outbound, Configure Your Solution, Manage Your Solution, SAP S/4HANA Cloud Public Edition, Central Business Configuration.   , KBA , CA-GTF-CSC-EDO-DE , Germany , CA-GTF-CSC-EDO , Electronic Document Processing Framework , CA-GTF-OC , SAP S/4HANA output management , Problem