Re: RMAIL bails out with coding-system-error

[Eli Zaretskii <eliz@is.elta.co.il>]

On Sun, 5 May 2002, Simon Josefsson wrote:

> Is this X-Coding-System header actually used by RMAIL for anything?

Yes, it is used to set the value of buffer-file-coding-system when you 
read the same message later.  Without this, RMAIL would have to 
repeatedly decode messages each time you display it; this would be a 
nuisance with long messages.

In addition, recording an encoding allows features like 
rmail-redecode-body, that lets users override bogus MIME headers.

> I think the header is a very bad idea and it should be removed.  There
> is a standard for interchanging non-ASCII data using email, and it is
> called MIME.  Inventing something new that is specific to emacs (and
> can even depend on which additional packages are installed..) is a
> perfect method to cause problems for users and make people reject the
> entire software because it doesn't follow standards.

IIRC, the X-Coding-System header is only written to the BABYL-formatted 
files Emacs keeps for itself, and then only in the summary part.  What 
kinds of problems do you envision with this, given that headers beginning 
with "X-" can be used by applications for their own purposes?

However, I'm not saying that this is the only possible way of recording 
the message encoding.  If there are more standard methods that can 
support the same features, we could consider switching to them.

> Gnus provides
> two supposedly standalone packages called Message and Emacs MIME which
> provides MIME encoding and decoding, can't RMAIL use them?

The difference between RMAIL and Gnus is that RMAIL stores only the 
decoded messages.  It doesn't keep the undecoded copy around.  But I 
don't know if this should prevent the change of the kind you suggest.