Brian E Carpenter wrote: > I am disturbed that the messy situation of X- headers, > created by RFC 2822's silence on the subject, has not > been fixed. As far as 2822 and 2822upd are concerned header fields not specified in 2822 or 2822upd resp. are covered by <optional-field> in section 3.6.8. This section does not talk about field-names starting with "X-" or not. > See http://www.ietf.org/IESG/APPEALS/klensin-response.txt > for an example of the issues that this silence can create. Gateways are always a difficult topic, and the 2822upd syntax *minus* obs-* constructs is hopefully friendlier to gateways than RFC 2822 *minus* obs-*. Including obs-* constructs: 2822upd is slightly better than before, a few RFC 822 #-cases not covered in 2822 are now accepted as obsolete, ASCII art with commas and similar oddities. > 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. RFC 822 said that X- headers will *not* be standardized, they are reserved for e-X-periments (my interpretation). Do you propose that 2822upd should copy this rule from RFC 822 ? Sorry, but I'm not sure what you are up to. An MTA not supporting header X-foobar is not forced to support header foobar only because it has no X-. As far as 2822upd is concerned both are <optional-field>s. Frank _______________________________________________ IETF mailing list IETF@xxxxxxxx https://www.ietf.org/mailman/listinfo/ietf