> This is the command to save drafts:
> 
>     notmuch-deliver Drafts --tag=draft \
>       --remove-tag=inbox --remove-tag=unread < message_file
> 
> Does it work if you run it manually?  Just make a dummy message_file
> with Date:, From:, To:, Subject: headers and a body.

The manual command works!

So I think I understand my problem. The reason is that in put in my
.config/bower/bower.conf:

notmuch_deliver=/bin/true

To solve the problem of "duplicated sent email" with Gmail:
http://support.google.com/mail/bin/answer.py?hl=en&answer=78892

But I didn't realize that notmuch_deliver was also used for postponed messages.

What is the good config? (I see that you're using gmail too :-) ...)?

thanks,
David