I am disturbed that the messy situation of X- headers, created by RFC 2822's silence on the subject, has not been fixed.
See http://www.ietf.org/IESG/APPEALS/klensin-response.txt for an example of the issues that this silence can create. I believe it would be appropriate to document that although X- headers are widely used, they are not part of the standard format and their treatment by Internet MTAs MUST NOT be relied on, unless registered under RFC 3864. Brian _______________________________________________ IETF mailing list IETF@ietf.org https://www.ietf.org/mailman/listinfo/ietf
