To avoid backscatter emails, on Postfix I set:
smtpd_reject_unlisted_sender = true
But this prevents the Odoo from sending some particular emails, since it uses some custom aliases as sender:
SMTPRecipientsRefused: {'myuser@mydomain.com': (550, b'5.1.0 <bounce+92-account.invoice-40@@mydomain.com>: Sender address rejected: @mydomain.com')}
How can I whitelist the Odoo server/app?