We need to send emails to a system that expects a specific email address. This address can be specified by ourselves but it has to be fixed!
Problem is that no matter what I try, the true email sender is not fixed, so it changes all the time. Key question: how can we set a true static outbound email address so the system receive our emails? Clearly you can set "on-behalf of", "reply To" etc... to hide the truth, but the system we need to support sees through this and sees the true email sender which is some sort of floating Salesforce email address that is extremely long.
As you can see here below.
Return-path: <email@example.com> Envelope-to: firstname.lastname@example.org Delivery-date: Tue, 12 May 2015 01:00:00 +0100 Received: from customer.domain.com ([xxx.xxx.xxx.xxx]) by smtp3.customerdomain.com with esmtps