Re: gnus doesn't encode non-ascii attachment filenames

[Katsumi Yamaoka <yamaoka@jpl.org>]

>>>>> In <8764njdbxi.fsf@emacsfans.org> Zhang Wei wrote:

> While composing mail, if I attach a file with non-ascii(chinese
> actually) filename, it's failed to correctly encode the filename.

> -- 
> Zhang Wei or Brep
> <brep@smth.org>

How is it incorrect?  Gnus does the RFC2231 encoding, that is
very correct.  However, in fact, many mail softwares don't
understand it.  They likely use the RFC2047-like encoding that
can understand only them.  That has not been standardized.  Gnus
can handle such an encoding, though.

Here's an extract from the Emacs MIME manual.  Does it help?

`rfc2047-encode-parameter'
     Encode a parameter in the RFC2047-like style.  This is a
     replacement for the `rfc2231-encode-string' function.  *Note
     rfc2231::.

     When attaching files as MIME parts, we should use the RFC2231
     encoding to specify the file names containing non-ASCII
     characters.  However, many mail softwares don't support it in
     practice and recipients won't be able to extract files with
     correct names.  Instead, the RFC2047-like encoding is acceptable
     generally.  This function provides the very RFC2047-like encoding,
     resigning to such a regrettable trend.  To use it, put the
     following line in your `~/.gnus.el' file:

          (defalias 'mail-header-encode-parameter 'rfc2047-encode-parameter)