From: David Mazieres <dm-list-email-notmuch@scs.stanford.edu>
To: mailinglists@nawaz.org, notmuch@notmuchmail.org
Subject: Re: Modify message after send...?
In-Reply-To: <878uacpwse.fsf@fester.com>
References: <878uacpwse.fsf@fester.com>
Reply-To: David Mazieres expires 2015-10-19 PDT
 <mazieres-ikhhtkgnuesn6x67wa9p6axshs@temporary-address.scs.stanford.edu>
Date: Tue, 21 Jul 2015 17:21:36 -0700
Message-ID: <87y4i9xcrz.fsf@ta.scs.stanford.edu>
MIME-Version: 1.0
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Precedence: list

mailinglists@nawaz.org writes:

> Hi,
>
> I use notmuch via Emacs.
>
> Here's what I want:
>
> When I hit C-c C-c to send a message, I'd like it to be passed to a
> script (likely a Python one, although I may consider an Elisp function
> if an external script is not possible) for modification of headers,
> before it is sent to the MTA (Postfix in my case). A bonus would be to
> have the modified message stored in the FCC location, instead of the
> original one.
>
> Is this possible? An alternative may be to modify the message /before/
> it goes to message-send-and-exit. I'm inexperienced in Elisp - would
> this be via what's called "advising"?
>
> BTW, all I really want to do is modify the From: field based on the
> recipients (for every email, with no default From). I'll welcome
> suggestions for existing ways to do that. I Googled a little, but didn't
> find a clear good solution. Furthermore, I expect over time the rules by
> which I pick the From: field will get more complex than my knowledge of
> Elisp.

For modifying the From field, I recommend doing it before you send the
message, as this gives you an opportunity to see what you are about to
send and possibly edit it by hand.

I do something like this using defadvice around notmuch-mua-mail, do
adjust things about my messages.  I also put a defadvice around
notmuch-call-notmuch-sexp to filter the To and Cc headers I get from
"notmuch reply" (because notmuch won't let me put wildcards in my
.notmuch-config file).

Finally, and possibly most relevant to you, I use a message-send-hook to
insert the Return-Path address and make a few more modifications before
sending a message.  Note that I only do this if there isn't already a
Return-Path header.  That way, if I type C-c C-c and don't like what I
see, I edit the result and send again, leaving the generated Return-Path
header, and this time it goes through unmodified.

David