Always CC specific messages to some people (send-hook and my_hdr)

[raf]

On Thu, Nov 12, 2020 at 05:58:01PM +0100, Raphaël Fournier-S'niehotta <raphael at raphaelfournier.net> wrote:

> Hello fellow mutt users,
> 
> When emailing to someone with mutt, I would like to have my messages
> automatically CC'd to someone. Typically, we are a team of academics
> working with a student, and I would like my exchanges with the student
> to be sent to others.
> 
> Mutt aliases seems to be on a "per field" basis. So I could use it to
> put my coworkers in an alias, but they would be in the "To:" field,
> not "CC".
> 
> I wanted to use a send-hook and the my_hdr variable, but it works for
> other fields (such as adding a "Organization: A Really Big Company,
> Anytown, USA", from the manual). But not for the CC field (the manual
> says: "note that my_hdr commands which modify recipient headers, or
> the message's subject, don't have any effect on the current message
> when executed from a send-hook").
> 
> Is there a workaround? Perhaps with the recent muttlisp?
> 
> Setting edit_headers to yes for all my messages(and having a nice
> macro in my editor) would not help, since I'd like such a behavior for
> only a fraction of my communication.
> 
> Thanks in advance!
> -- 
> Raphaël Fournier-S'niehotta
> http://raphael.fournier-sniehotta.fr/apropos

Hi,

I needed to do something very much like this. I needed
to automatically Cc: all my work-related emails. But I
found that the problem with doing it entirely in mutt
was that the hooks that looked most likely to assist
couldn't affect the recipient addresses (due to the
order in which things happen inside mutt). That's the
same limitation that you encountered.

I had configured mutt to automatically set my from
address, depending on where the email is being sent to.
For example, when sending to this list, From: is
mutt at raf.org. When sending to a work-related address
(e.g. colleague, vendor, government), From: is my work
address. e.g.:

  send-hook '~t @work\.com\.au'   'my_hdr From: Me <me at work.com.au>'
  send-hook '~t @vendor\.com\.au' 'my_hdr From: Me <me at work.com.au>'
  send-hook '~t @ato\.gov\.au'    'my_hdr From: My Self <me at work.com.au>'

Then, the auto-cc is handled by an editor script:

  set editor = "~/bin/mutt-editor"

Editing headers is a requirement:

  set edit_hdrs

But no in-editor macros are needed.

The editor script looks like this (~/bin/mutt-editor):

  #!/bin/sh

  # mutt-editor - Preprocessor/editor/postprocessor for mutt

  # Delete empty recipient headers
  perl -pi -e '$_ = "" if /^(Cc|Bcc|Reply-To): $/' "$@"

  # Add Cc: headers automatically when necessary
  mutt-autocc drew at work.com.au "$@"
  mutt-autocc kim at work.com.au "$@"
  mutt-autocc sam at work.com.au "$@"

  # Launch the editor
  ${VISUAL:-${EDITOR:-vi}} "$@"

  # Add Cc: headers automatically when necessary
  mutt-autocc drew at work.com.au "$@"
  mutt-autocc kim at work.com.au "$@"
  mutt-autocc sam at work.com.au "$@"

The mutt-autocc script automatically adds a Cc: header
if the From: address is my work address, or if the To:
or Cc: headers contain work-related domains, and if the
intended new recipient isn't already going to receive
the email. It looks like this (~/bin/mutt-autocc):

  #!/usr/bin/perl -i
  use warnings;
  use strict;

  # mutt-autocc - Mail message preprocesor/filter
  # to automatically add a Cc: header when
  # sending/replying/forwarding from my work domain
  # or to an obviously work-related domain.
  #
  # usage: mutt-autocc cc at address filename

  my $cc_address = shift @ARGV;
  my $from_domain = qr/\@work\.com\.au\b/;
  my $to_domains = qr/\@(?:work\.com\.au|vendor\.com\.au|ato\.gov\.au)\b/;
  my $from_match = 0;
  my $to_match = 0;
  my $already = 0;

  while (<>)
  {
      # Does the From: header contain the from_domain?
      $from_match = 1 if /^From: .*$from_domain/i;
      # Do the To/Cc headers contain any of the to_domains?
      $to_match = 1 if /^(?:To|Cc): .*$to_domains/i;
      # Is the cc_address already going to receive the email?
      $already = 1 if /^(?:To|Cc|Bcc): .*\b\Q$cc_address\E\b/i;
      $already = 1 if /^  .*\b\Q$cc_address\E\b/i;
      # Add Cc: header if necessary once we've seen the recipient headers
      $already = 1, print("Cc: $cc_address\n") if /^Subject: / && ($from_match || $to_match) && !$already;
      # Print all lines
      print;
  }

  # vi:set ts=4 sw=4:

Calling it before the real editor would usually be
enough to add the Cc: headers before I start editing
the email. But if I have missed any destination
addresses in my send hooks, and I need to manually
change the From: address to my work address, then the
postprocessing phase will handle the rest. The same
is true if the email wasn't originally being sent
to the relevant recipient, but they are added manually
during the editor session.

Warning: As Cameron so rightly pointed out,
automatically cc-ing can lead to unintended emails
being sent. Especially when you have configured mutt to
automatically set your From: address for one email, and
it just stays that way by default for the next email.
And even more especially when addresses can be added by
a postprocessor after the editor.

So, I strongly recommend, that if you use an approach
like this, that after you have completed editing your
email, and leave the editor, you go back into the
editor (with the 'e' keystroke), to check the email
again before sending it (with the 'y' keystroke).

However, if you only need to auto-cc based on the To:
header (and not the From: header), this probably isn't
a concern, and you probably don't have to be so
careful. But you'll need to assess the risks yourself.

Also note that mutt will coalesce multiple Cc: headers
into a single one after editing, so you don't need to
worry about creating multiple Cc: headers.

I hope that helps. If you think this approach will do
what you need, but you'd like help modifying the perl
to match your exact needs, let me know and I'll modify
it for you. I'm assuming that your environment is UNIXy
enough for all this to be possible. That might not be
the case.

cheers,
raf