I must set my own Message-ID in the header of an email (to send with NetEmailSend). I can use self.messagID=myownvalue (basicly a GUID), but it's useless because the class always overwrites it.
Background: I send an Email and the receiver sends one or more Emails back (automatically) which belongs to the sent Email. The received Mails can come in arbitrary order. I must match these Mails like a "1 to many" relation.
I tried self.ExtraHeader, this works but the Message-ID entry generated by the class is the first line in the sent Email. My entry via ExtraHeader comes later and so I guess it's ignored by the Receiver.
What is the secret or background of setting an own Message-ID ?