Re: X-coding-system incompatibility, and workaround

[Eli Zaretskii <eliz@gnu.org>]

> From: Richard Stallman <rms@gnu.org>
> Date: Fri, 09 Nov 2007 22:00:11 -0500
> Cc: emacs-devel@gnu.org
> 
>     Could you modify future versions of emacs to try to avoid using
>     coding systems that are not defined on earlier versions?
> 
> I don't know if this is possible.  To think about the question
> we would need to figure out WHY it uses those coding systems.

Rmail uses these coding systems because the Babyl mail file requests
them in the X-coding-system header.  This header is generated by Rmail
when it decodes the mail message for the first time.  Thus, the value
of the header is very tightly coupled with which coding-systems are
supported by Emacs that produced the Babyl file.

I don't see how this can be solved: as Emacs is developed, support for
new encodings is added to it, and it doesn't make sense to limit such
development for a marginal situation such as this one (sharing the
same mail file between two different versions of Emacs).

As a workaround, I can suggest to run unrmail on the Babyl file in the
Emacs that wrote it, and then run Rmail on the result in the other
version of Emacs (that is, share the mail file in the mbox format).
That is, if the workarounds the OP already discovered (which are
perfectly valid, btw) are inconvenient for some reason.

Btw, for windows-1252-unix, you need to make it an alias to Latin-1.