Stefan Claas:
postfix should modify outgoing email headers that *only* go to mail2news gateways, using the email gateway addresses for parsing, so that the right part of the message ID, after the @ charachter, will be modified with a defined string.
Do you mean "should modify outgoing email headers that only go to mail2news gateways" or "should only modify outgoing email headers that go to mail2news gateways"? What should happen if an email is sent both to one or more regular email addresses and to a mail2news gateway?
What you want to do seems to be a job for a milter: Depending on the "RCPT TO" line (or on the "To:" header), modify the "Message-ID:" header. Such a conditional header modification cannot be done from inside Postfix. The only available mechanism to modify email headers is smtp_header_checks, but it works line by line: "Each message header or message body line is compared against a list of patterns. When a match is found the corresponding action is executed, and the matching process is repeated for the next message header or message body line."
Gregory
