tm supports MIME charset for September Gnus running on Mule. Mule
already code-converts when reading and writing file, however it
requires to read/write with no code-conversion and code-conversion
must be done when a content is displayed after MIME parsing is done.
Because MIME charset is specified for content, not for message. So a
message can have different charset contents.

  For only nntp, it is easy. But now September Gnus has various kinds
of nn* back ends. So it is difficult to support only tm-sgnus.el.

  Anyway, I made a patch for nn*. It adds an alias and two hooks.
Alias `nnheader-insert-raw-file-contents' is to read with no code
conversion. It is used for read mailbox file or separated article
file.

  `nnheader-load-hook' is for tm-sgnus.el. It is used to redefine
`nnheader-insert-raw-file-contents'. (XEmacs 19.13 does not have
function `eval-after-load')

  `nnmail-prepare-save-mail-hook' is to set coding-system is *noconv*.
There are various `nn*-prepare-save-mail-hook', old tm-sgnus added to
every hooks, however if new nn* is created, tm-sgnus must be fixed. It 
is not good way, I think. So please add one hook before mail saving.

  In addition, tm 7.52.2 supports this patch.

  Thanks,