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You have to create an Org Wide Address as explained by salesforce in this article: https://help.salesforce.com/articleView?id=emailadmin_manage_orgwide_email_addresses.htm&type=5
You have to get the id of the newly created record. The easiest solution is copying it from the URL address bar. You can also run a query (SOQL) to the system to show the Id of the record. The ID should start with 0D2.
Code Block SELECT Id, Address, DisplayName from OrgWideEmailAddress
Copy-paste this ID into the field on your administration named “Organization Wide Email” and save the administration.
Account details
For an account to qualify for E-billing some fields on the account have to be populated.
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