Message mode with non-ASCII signature

[Lele Gaifax]

Hi all,

as you can see below, my signature contains some non-ASCII characters,
and it is stored as UTF-8 (I have `(prefer-coding-system 'utf-8)` in my
.emacs.el) in my home as ~/.signature.

Recently I started using notmuch with Emacs as the main MUA, using
message-mode to send emails.

Everything works great, except that when I "forward" an email message:
in that case, the "*unsent mail*" buffer contains the original message
within a "#mml" tag, followed by my signature, apparently appended as
binary (e.g. instead of "vivrò" I see "vivr\303\262"). When I try to
send it, I get the "Unreadable characters" prompt...

I quickly inspected what notmuch-show-forward-message does, but AFAICT
it does very little, delegating most of the work to message-mode: that's
why I'm asking here first.

I also tried tweaking the message-default-charset, changing it from nil
to utf-8, with the very same result.

I'm using Emacs 24.4.51 compiled a few days ago, if that matters.

Thank you for any hint,
ciao, lele.
-- 
nickname: Lele Gaifax | Quando vivrò di quello che ho pensato ieri
real: Emanuele Gaifas | comincerò ad aver paura di chi mi copia.
lele@metapensiero.it  |                 -- Fortunato Depero, 1929.