Add --list option to reply Mailing list

Provide an option to the reply command ':reply --list':
* In reply to someone to a list (not you), it will take if available
(Reply-To, X-BeenThere or X-Mailing-List).
* In the rare reply to you sending to a list, it will take the To which
is the list mail.

This work start/rebase/refactor from this 'old' (3 years) PR on github:
https://github.com/pazz/alot/pull/479#issuecomment-152750321

2 files changed, 22 insertions, 1 deletions

diff --git a/alot/commands/thread.py b/alot/commands/thread.py
index 1d39fc4d..21e2721b 100644
--- a/alot/commands/thread.py
+++ b/alot/commands/thread.py
@@ -105,6 +105,7 @@ def determine_sender(mail, action='reply'):
 
 @registerCommand(MODE, 'reply', arguments=[
     (['--all'], {'action': 'store_true', 'help': 'reply to all'}),
+    (['--list'], {'action': 'store_true', 'dest': 'listreply', 'help': 'reply to list'}),
     (['--spawn'], {'action': BooleanAction, 'default': None,
                    'help': 'open editor in new window'})])
 class ReplyCommand(Command):
@@ -112,17 +113,20 @@ class ReplyCommand(Command):
     """reply to message"""
     repeatable = True
 
-    def __init__(self, message=None, all=False, spawn=None, **kwargs):
+    def __init__(self, message=None, all=False, listreply=False, spawn=None, **kwargs):
         """
         :param message: message to reply to (defaults to selected message)
         :type message: `alot.db.message.Message`
         :param all: group reply; copies recipients from Bcc/Cc/To to the reply
         :type all: bool
+        :param listreply: reply to list
+        :type listreply: bool
         :param spawn: force spawning of editor in a new terminal
         :type spawn: bool
         """
         self.message = message
         self.groupreply = all
+        self.listreply = listreply
         self.force_spawn = spawn
         Command.__init__(self, **kwargs)
 
@@ -212,6 +216,22 @@ class ReplyCommand(Command):
 
         to = ', '.join(recipients)
         logging.debug('reply to: %s' % to)
+
+        if self.listreply:
+            # To choose the target of the reply --list
+            # Reply-To is standart reply target RFC 2822:, RFC 1036: 2.2.1
+            # X-BeenThere is needed by sourceforge ML also winehq
+            # X-Mailing-List is also standart and is used by git-send-mail
+            to = mail['Reply-To'] or mail['X-BeenThere'] or mail['X-Mailing-List']
+            # Some mail server (gmail) will not resend you own mail, so you have
+            # to deal with the one in sent
+            if to is None:
+                to = mail['To']
+            logging.debug('mail list reply to: %s' % to)
+            # Cleaning the 'To' in this case
+            envelope.__delitem__('To')
+
+        # Finally setup the 'To' header
         envelope.add('To', decode_header(to))
 
         # if any of the recipients is a mailinglist that we are subscribed to,
diff --git a/docs/source/usage/modes/thread.rst b/docs/source/usage/modes/thread.rst
index e849c3c3..1db63f61 100644
--- a/docs/source/usage/modes/thread.rst
+++ b/docs/source/usage/modes/thread.rst
@@ -167,6 +167,7 @@ The following commands are available in thread mode
 
     optional arguments
         :---all: reply to all.
+        :---list: reply to list.
         :---spawn: open editor in new window.
 
 .. _cmd.thread.save: