When I send out a E-Mail from my ERPNext installation it always shows the Message-ID with my erpnext machine local url (for example erpnext.vm). Also the X-Frappe-Site Tag is shown in the E-Mail header.
in conclusion:
- Is there any way to customize Message-ID in sent Emails
- Is there any way to delete the into X-Frappe-Site in Emails
For anyone who wants to work around I answer that question for security reasons because as you can guess that you might not want to tell any customer from which ERP system there messages are sent.