Massive digester rework.

This moves actual digest creation and sending into a new queue runner.  That
way, digest creation does not block the main incoming processor.  Lots of code
clean up and reorganization too, and many fixes.

digest_last_sent_at: Make this a DateTime
digest_size_threshold: Make this a Float
digest_volume_frequency: Make this an Enum

DigestFrequency: new enum

Fix up IMailingList interface to reflect reality.

In Runner base class, allow for msg.get_sender() to return a False value.  If
this happens (as it can with the empty marker messages used to signal the
digester that there's work to do), just use the list's preferred language.

Give the retry.py and incoming.py queue runner modules some proper epilogues.

The EmptyingRunner (for testing) logs itself as the runner its wrapping.

The digest file name now ends in .mmdf since that's the format we're using.

Add 'create_list' to doctest globals.

Add a Mailbox class to add support for the context manager protocol.

5 files changed, 879 insertions, 10 deletions

diff --git a/src/mailman/queue/__init__.py b/src/mailman/queue/__init__.py
index 6094bda9e..ead077e90 100644
--- a/src/mailman/queue/__init__.py
+++ b/src/mailman/queue/__init__.py
@@ -428,10 +428,13 @@ class Runner:
         # special care to reset the defaults, otherwise subsequent messages
         # may be translated incorrectly.
         sender = msg.get_sender()
-        member = mlist.members.get_member(sender)
-        language = (member.preferred_language
-                    if member is not None
-                    else mlist.preferred_language)
+        if sender:
+            member = mlist.members.get_member(sender)
+            language = (member.preferred_language
+                        if member is not None
+                        else mlist.preferred_language)
+        else:
+            language = mlist.preferred_language
         with i18n.using_language(language):
             msgdata['lang'] = language
             keepqueued = self._dispose(mlist, msg, msgdata)
diff --git a/src/mailman/queue/digest.py b/src/mailman/queue/digest.py
new file mode 100644
index 000000000..e066be993
--- /dev/null
+++ b/src/mailman/queue/digest.py
@@ -0,0 +1,365 @@
+# Copyright (C) 2009 by the Free Software Foundation, Inc.
+#
+# This file is part of GNU Mailman.
+#
+# GNU Mailman is free software: you can redistribute it and/or modify it under
+# the terms of the GNU General Public License as published by the Free
+# Software Foundation, either version 3 of the License, or (at your option)
+# any later version.
+#
+# GNU Mailman is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# GNU Mailman.  If not, see <http://www.gnu.org/licenses/>.
+
+"""Digest queue runner."""
+
+from __future__ import absolute_import, unicode_literals
+
+__metaclass__ = type
+__all__ = [
+    'DigestRunner',
+    ]
+
+
+import re
+
+# cStringIO doesn't support unicode.
+from StringIO import StringIO
+from contextlib import nested
+from copy import deepcopy
+from email.header import Header
+from email.message import Message
+from email.mime.message import MIMEMessage
+from email.mime.multipart import MIMEMultipart
+from email.mime.text import MIMEText
+from email.utils import formatdate, getaddresses, make_msgid
+
+from mailman import i18n
+from mailman.Utils import GetCharSet, maketext, oneline, wrap
+from mailman.config import config
+from mailman.core.errors import DiscardMessage
+from mailman.i18n import _
+from mailman.pipeline.decorate import decorate
+from mailman.pipeline.scrubber import process as scrubber
+from mailman.queue import Runner
+from mailman.utilities.mailbox import Mailbox
+
+
+
+class Digester:
+    """Base digester class."""
+
+    def __init__(self, mlist, volume, digest_number):
+        self._mlist = mlist
+        self._charset = GetCharSet(mlist.preferred_language)
+        # This will be used in the Subject, so use $-strings.
+        realname = mlist.real_name
+        issue = digest_number
+        self._digest_id = _('$realname Digest, Vol $volume, Issue $issue')
+        self._subject = Header(self._digest_id,
+                               self._charset,
+                               header_name='Subject')
+        self._message = self._make_message()
+        self._message['From'] = mlist.request_address
+        self._message['Subject'] = self._subject
+        self._message['To'] = mlist.posting_address
+        self._message['Reply-To'] = mlist.posting_address
+        self._message['Date'] = formatdate(localtime=True)
+        self._message['Message-ID'] = make_msgid()
+        # In the rfc1153 digest, the masthead contains the digest boilerplate
+        # plus any digest header.  In the MIME digests, the masthead and
+        # digest header are separate MIME subobjects.  In either case, it's
+        # the first thing in the digest, and we can calculate it now, so go
+        # ahead and add it now.
+        self._masthead = maketext(
+            'masthead.txt', dict(
+                real_name=mlist.real_name,
+                got_list_email=mlist.posting_address,
+                got_listinfo_url=mlist.script_url('listinfo'),
+                got_request_email=mlist.request_address,
+                got_owner_email=mlist.owner_address,
+                ),
+            mlist=mlist)
+        # Set things up for the table of contents.
+        self._header = decorate(mlist, mlist.digest_header)
+        self._toc = StringIO()
+        print >> self._toc, _("Today's Topics:\n")
+
+    def add_to_toc(self, msg, count):
+        """Add a message to the table of contents."""
+        subject = msg.get('subject', _('(no subject)'))
+        subject = oneline(subject, in_unicode=True)
+        # Don't include the redundant subject prefix in the toc
+        mo = re.match('(re:? *)?({0})'.format(
+            re.escape(self._mlist.subject_prefix)),
+                      subject, re.IGNORECASE)
+        if mo:
+            subject = subject[:mo.start(2)] + subject[mo.end(2):]
+        # Take only the first author we find.
+        username = ''
+        addresses = getaddresses(
+            [oneline(msg.get('from', ''), in_unicode=True)])
+        if addresses:
+            username = addresses[0][0]
+            if not username:
+                username = addresses[0][1]
+        if username:
+            username = ' ({0})'.format(username)
+        lines = wrap('{0:2}. {1}'. format(count, subject), 65).split('\n')
+        # See if the user's name can fit on the last line
+        if len(lines[-1]) + len(username) > 70:
+            lines.append(username)
+        else:
+            lines[-1] += username
+        # Add this subject to the accumulating topics
+        first = True
+        for line in lines:
+            if first:
+                print >> self._toc, ' ', line
+                first = False
+            else:
+                print >> self._toc, '     ', line.lstrip()
+
+    def add_message(self, msg, count):
+        """Add the message to the digest."""
+        # We do not want all the headers of the original message to leak
+        # through in the digest messages.
+        keepers = {}
+        for header in self._keepers:
+            keepers[header] = msg.get_all(keeper, [])
+        # Remove all the unkempt <wink> headers.  Use .keys() to allow for
+        # destructive iteration...
+        for header in msg.keys():
+            del msg[header]
+        # ... and add them in the designated order.
+        for header in self._keepers:
+            for value in keepers[header]:
+                msg[header] = value
+        # Add some useful extra stuff.
+        msg['Message'] = unicode(count)
+
+
+
+class MIMEDigester(Digester):
+    """A MIME digester."""
+
+    def __init__(self, mlist, volume, digest_number):
+        super(MIMEDigester, self).__init__(mlist, volume, digest_number)
+        masthead = MIMEText(self._masthead.encode(self._charset),
+                            _charset=self._charset)
+        masthead['Content-Description'] = self._subject
+        self._message.attach(masthead)
+        # Add the optional digest header.
+        if mlist.digest_header:
+            header = MIMEText(self._header.encode(self._charset),
+                              _charset=self._charset)
+            header['Content-Description'] = _('Digest Header')
+            self._message.attach(header)
+        # Calculate the set of headers we're to keep in the MIME digest.
+        self._keepers = set(config.digests.mime_digest_keep_headers.split())
+
+    def _make_message(self):
+        return MIMEMultipart('mixed')
+
+    def add_toc(self, count):
+        """Add the table of contents."""
+        toc_text = self._toc.getvalue()
+        try:
+            toc_part = MIMEText(toc_text.encode(self._charset),
+                                _charset=self._charset)
+        except UnicodeError:
+            toc_part = MIMEText(toc_text.encode('utf-8'), _charset='utf-8')
+        toc_part['Content-Description']= _("Today's Topics ($count messages)")
+        self._message.attach(toc_part)
+
+    def add_message(self, msg, count):
+        """Add the message to the digest."""
+        # Make a copy of the message object, since the RFC 1153 processing
+        # scrubs out attachments.
+        self._message.attach(MIMEMessage(deepcopy(msg)))
+
+    def finish(self):
+        """Finish up the digest, producing the email-ready copy."""
+        if self._mlist.digest_footer:
+            footer_text = decorate(self._mlist, self._mlist.digest_footer)
+            footer = MIMEText(footer_text.encode(self._charset),
+                              _charset=self._charset)
+            footer['Content-Description'] = _('Digest Footer')
+            self._message.attach(footer)
+        # This stuff is outside the normal MIME goo, and it's what the old
+        # MIME digester did.  No one seemed to complain, probably because you
+        # won't see it in an MUA that can't display the raw message.  We've
+        # never got complaints before, but if we do, just wax this.  It's
+        # primarily included for (marginally useful) backwards compatibility.
+        self._message.postamble = _('End of ') + self._digest_id
+        return self._message
+
+
+
+class RFC1153Digester(Digester):
+    """A digester of the format specified by RFC 1153."""
+
+    def __init__(self, mlist, volume, digest_number):
+        super(RFC1153Digester, self).__init__(mlist, volume, digest_number)
+        self._separator70 = '-' * 70
+        self._separator30 = '-' * 30
+        self._text = StringIO()
+        print >> self._text, self._masthead
+        print >> self._text
+        # Add the optional digest header.
+        if mlist.digest_header:
+            print >> self._text, self._header
+            print >> self._text
+        # Calculate the set of headers we're to keep in the RFC1153 digest.
+        self._keepers = set(config.digests.plain_digest_keep_headers.split())
+
+    def _make_message(self):
+        return Message()
+
+    def add_toc(self, count):
+        """Add the table of contents."""
+        print >> self._text, self._toc.getvalue()
+        print >> self._text
+        print >> self._text, self._separator70
+        print >> self._text
+
+    def add_message(self, msg, count):
+        """Add the message to the digest."""
+        if count > 1:
+            print >> self._text, self._separator30
+            print >> self._text
+        # Scrub attachements.
+        try:
+            msg = scrubber(self._mlist, msg)
+        except DiscardMessage:
+            print >> self._text, _('[Message discarded by content filter]')
+            return
+        # Each message section contains a few headers.
+        for header in config.digests.plain_digest_keep_headers.split():
+            if header in msg:
+                value = oneline(msg[header], in_unicode=True)
+                value = wrap('{0}: {1}'.format(header, value))
+                value = '\n\t'.join(value.split('\n'))
+                print >> self._text, value
+        print >> self._text
+        # Add the payload.  If the decoded payload is empty, this may be a
+        # multipart message.  In that case, just stringify it.
+        payload = msg.get_payload(decode=True)
+        payload = (payload if payload else msg.as_string().split('\n\n', 1)[1])
+        try:
+            charset = msg.get_content_charset('us-ascii')
+            payload = unicode(payload, charset, 'replace')
+        except (LookupError, TypeError):
+            # Unknown or empty charset.
+            payload = unicode(payload, 'us-ascii', 'replace')
+        print >> self._text, payload
+        if not payload.endswith('\n'):
+            print >> self._text
+
+    def finish(self):
+        """Finish up the digest, producing the email-ready copy."""
+        if self._mlist.digest_footer:
+            footer_text = decorate(self._mlist, self._mlist.digest_footer)
+            # This is not strictly conformant RFC 1153.  The trailer is only
+            # supposed to contain two lines, i.e. the "End of ... Digest" line
+            # and the row of asterisks.  If this screws up MUAs, the solution
+            # is to add the footer as the last message in the RFC 1153 digest.
+            # I just hate the way that VM does that and I think it's confusing
+            # to users, so don't do it unless there's a clamor.
+            print >> self._text, self._separator30
+            print >> self._text
+            print >> self._text, footer_text
+            print >> self._text
+        # Add the sign-off.
+        sign_off = _('End of ') + self._digest_id
+        print >> self._text, sign_off
+        print >> self._text, '*' * len(sign_off)
+        # If the digest message can't be encoded by the list character set,
+        # fall back to utf-8.
+        text = self._text.getvalue()
+        try:
+            self._message.set_payload(text.encode(self._charset),
+                                      charset=self._charset)
+        except UnicodeError:
+            self._message.set_payload(text.encode('utf-8'), charset='utf-8')
+        return self._message
+
+
+
+class DigestRunner(Runner):
+    """The digest queue runner."""
+
+    def _dispose(self, mlist, msg, msgdata):
+        """See `IRunner`."""
+        volume = msgdata['volume']
+        digest_number = msgdata['digest_number']
+        with nested(Mailbox(msgdata['digest_path']),
+                    i18n.using_language(mlist.preferred_language)) as (
+            mailbox, language):
+            # Create the digesters.
+            mime_digest = MIMEDigester(mlist, volume, digest_number)
+            rfc1153_digest = RFC1153Digester(mlist, volume, digest_number)
+            # Cruise through all the messages in the mailbox, first building
+            # the table of contents and accumulating Subject: headers and
+            # authors.  The question really is whether it's better from a
+            # performance and memory footprint to go through the mailbox once
+            # and cache the messages in a list, or to cruise through the
+            # mailbox twice.  We'll do the latter, but it's a complete guess.
+            count = None
+            for count, (key, message) in enumerate(mailbox.iteritems(), 1):
+                mime_digest.add_to_toc(message, count)
+                rfc1153_digest.add_to_toc(message, count)
+            assert count is not None, 'No digest messages?'
+            # Add the table of contents.
+            mime_digest.add_toc(count)
+            rfc1153_digest.add_toc(count)
+            # Cruise through the set of messages a second time, adding them to
+            # the actual digest.
+            for count, (key, message) in enumerate(mailbox.iteritems(), 1):
+                mime_digest.add_message(message, count)
+                rfc1153_digest.add_message(message, count)
+            # Finish up the digests.
+            mime = mime_digest.finish()
+            rfc1153 = rfc1153_digest.finish()
+        # Calculate the recipients lists
+        mime_recipients = set()
+        rfc1153_recipients = set()
+        # When someone turns off digest delivery, they will get one last
+        # digest to ensure that there will be no gaps in the messages they
+        # receive.
+        digest_members = set(mlist.digest_members.members)
+        for address in mlist.one_last_digest:
+            member = mlist.digest_members.get_member(address)
+            if member:
+                digest_members.add(member)
+        for member in digest_members:
+            if member.delivery_status <> DeliveryStatus.enabled:
+                continue
+            # Send the digest to the case-preserved address of the digest
+            # members.
+            email_address = member.address.original_address
+            if member.delivery_mode == DeliveryMode.plaintext_digests:
+                rfc1153_recipients.add(email_address)
+            elif member.delivery_mode == DeliveryMode.mime_digests:
+                mime_recipients.add(email_address)
+            else:
+                raise AssertionError(
+                    'Digest member "{0}" unexpected delivery mode: {1}'.format(
+                        email_address, member.delivery_mode))
+        # Send the digests to the virgin queue for final delivery.
+        queue = config.switchboards['virgin']
+        queue.enqueue(mime,
+                      recips=mime_recipients,
+                      listname=mlist.fqdn_listname,
+                      isdigest=True)
+        queue.enqueue(rfc1153,
+                      recips=rfc1153_recipients,
+                      listname=mlist.fqdn_listname,
+                      isdigest=True)
+        # Now that we've delivered the last digest to folks who were waiting
+        # for it, clear that recipient set.
+        mlist.one_last_digest.clear()
diff --git a/src/mailman/queue/docs/digester.txt b/src/mailman/queue/docs/digester.txt
new file mode 100644
index 000000000..487549e90
--- /dev/null
+++ b/src/mailman/queue/docs/digester.txt
@@ -0,0 +1,484 @@
+Digesting
+=========
+
+Mailman crafts and sends digests by a separate digest queue runner process.
+This starts by a number of messages being posted to the mailing list.
+
+    >>> mlist = create_list('test@example.com')
+    >>> mlist.digest_size_threshold = 0.5
+    >>> mlist.volume = 1
+    >>> mlist.next_digest_number = 1
+    >>> size = 0
+
+    >>> from string import Template
+    >>> process = config.handlers['to-digest'].process
+    >>> for i in range(1, 5):
+    ...     text = Template("""\
+    ... From: aperson@example.com
+    ... To: xtest@example.com
+    ... Subject: Test message $i
+    ...
+    ... Here is message $i
+    ... """).substitute(i=i)
+    ...     msg = message_from_string(text)
+    ...     process(mlist, msg, {})
+    ...     size += len(text)
+    ...     if size >= mlist.digest_size_threshold * 1024:
+    ...         break
+
+The queue runner gets kicked off when a marker message gets dropped into the
+digest queue.  The message metadata points to the mailbox file containing the
+messages to put in the digest.
+
+    >>> digestq = config.switchboards['digest']
+    >>> len(digestq.files)
+    1
+
+    >>> from mailman.testing.helpers import get_queue_messages
+    >>> entry = get_queue_messages('digest')[0]
+
+The marker message is empty.
+
+    >>> print entry.msg.as_string()
+
+But the message metadata has a reference to the digest file.
+
+    >>> dump_msgdata(entry.msgdata)
+    _parsemsg    : False
+    digest_number: 1
+    digest_path  : .../lists/test@example.com/digest.1.1.mmdf
+    listname     : test@example.com
+    version      : 3
+    volume       : 1
+
+    # Put the messages back in the queue for the runner to handle.
+    >>> filebase = digestq.enqueue(entry.msg, entry.msgdata)
+
+There are 4 messages in the digest.
+
+    >>> from mailman.utilities.mailbox import Mailbox
+    >>> sum(1 for item in Mailbox(entry.msgdata['digest_path']))
+    4
+
+When the queue runner runs, it processes the digest mailbox, crafting both the
+plain text (RFC 1153) digest and the MIME digest.
+
+    >>> from mailman.queue.digest import DigestRunner
+    >>> from mailman.testing.helpers import make_testable_runner
+    >>> runner = make_testable_runner(DigestRunner)
+    >>> runner.run()
+
+The digest runner places both digests into the virgin queue for final
+delivery.
+
+    >>> messages = get_queue_messages('virgin')
+    >>> len(messages)
+    2
+
+The MIME digest is a multipart, and the RFC 1153 digest is the other one.
+
+    >>> if messages[0].msg.is_multipart():
+    ...     mime = messages[0].msg
+    ...     rfc1153 = messages[1].msg
+    ... else:
+    ...     mime = messages[1].msg
+    ...     rfc1153 = messages[0].msg
+
+The MIME digest has lots of good stuff, all contained in the multipart.
+
+    >>> print mime.as_string()
+    Content-Type: multipart/mixed; boundary="===============...=="
+    MIME-Version: 1.0
+    From: test-request@example.com
+    Subject: Test Digest, Vol 1, Issue 1
+    To: test@example.com
+    Reply-To: test@example.com
+    Date: ...
+    Message-ID: ...
+    <BLANKLINE>
+    --===============...==
+    Content-Type: text/plain; charset="us-ascii"
+    MIME-Version: 1.0
+    Content-Transfer-Encoding: 7bit
+    Content-Description: Test Digest, Vol 1, Issue 1
+    <BLANKLINE>
+    Send Test mailing list submissions to
+    	test@example.com
+    <BLANKLINE>
+    To subscribe or unsubscribe via the World Wide Web, visit
+    	http://lists.example.com/listinfo/test@example.com
+    or, via email, send a message with subject or body 'help' to
+    	test-request@example.com
+    <BLANKLINE>
+    You can reach the person managing the list at
+    	test-owner@example.com
+    <BLANKLINE>
+    When replying, please edit your Subject line so it is more specific
+    than "Re: Contents of Test digest..."
+    <BLANKLINE>
+    --===============...==
+    Content-Type: text/plain; charset="us-ascii"
+    MIME-Version: 1.0
+    Content-Transfer-Encoding: 7bit
+    Content-Description: Today's Topics (4 messages)
+    <BLANKLINE>
+    Today's Topics:
+    <BLANKLINE>
+       1. Test message 1 (aperson@example.com)
+       2. Test message 2 (aperson@example.com)
+       3. Test message 3 (aperson@example.com)
+       4. Test message 4 (aperson@example.com)
+    <BLANKLINE>
+    --===============...==
+    Content-Type: message/rfc822
+    MIME-Version: 1.0
+    <BLANKLINE>
+    From: aperson@example.com
+    To: xtest@example.com
+    Subject: Test message 1
+    <BLANKLINE>
+    Here is message 1
+    <BLANKLINE>
+    --===============...==
+    Content-Type: message/rfc822
+    MIME-Version: 1.0
+    <BLANKLINE>
+    From: aperson@example.com
+    To: xtest@example.com
+    Subject: Test message 2
+    <BLANKLINE>
+    Here is message 2
+    <BLANKLINE>
+    --===============...==
+    Content-Type: message/rfc822
+    MIME-Version: 1.0
+    <BLANKLINE>
+    From: aperson@example.com
+    To: xtest@example.com
+    Subject: Test message 3
+    <BLANKLINE>
+    Here is message 3
+    <BLANKLINE>
+    --===============...==
+    Content-Type: message/rfc822
+    MIME-Version: 1.0
+    <BLANKLINE>
+    From: aperson@example.com
+    To: xtest@example.com
+    Subject: Test message 4
+    <BLANKLINE>
+    Here is message 4
+    <BLANKLINE>
+    --===============...==
+    Content-Type: text/plain; charset="us-ascii"
+    MIME-Version: 1.0
+    Content-Transfer-Encoding: 7bit
+    Content-Description: Digest Footer
+    <BLANKLINE>
+    _______________________________________________
+    Test mailing list
+    test@example.com
+    http://lists.example.com/listinfo/test@example.com
+    <BLANKLINE>
+    --===============...==--
+
+The RFC 1153 contains the digest in a single plain text message.
+
+    >>> print rfc1153.as_string()
+    From: test-request@example.com
+    Subject: Test Digest, Vol 1, Issue 1
+    To: test@example.com
+    Reply-To: test@example.com
+    Date: ...
+    Message-ID: ...
+    MIME-Version: 1.0
+    Content-Type: text/plain; charset="us-ascii"
+    Content-Transfer-Encoding: 7bit
+    <BLANKLINE>
+    Send Test mailing list submissions to
+    	test@example.com
+    <BLANKLINE>
+    To subscribe or unsubscribe via the World Wide Web, visit
+    	http://lists.example.com/listinfo/test@example.com
+    or, via email, send a message with subject or body 'help' to
+    	test-request@example.com
+    <BLANKLINE>
+    You can reach the person managing the list at
+    	test-owner@example.com
+    <BLANKLINE>
+    When replying, please edit your Subject line so it is more specific
+    than "Re: Contents of Test digest..."
+    <BLANKLINE>
+    <BLANKLINE>
+    Today's Topics:
+    <BLANKLINE>
+       1. Test message 1 (aperson@example.com)
+       2. Test message 2 (aperson@example.com)
+       3. Test message 3 (aperson@example.com)
+       4. Test message 4 (aperson@example.com)
+    <BLANKLINE>
+    <BLANKLINE>
+    ----------------------------------------------------------------------
+    <BLANKLINE>
+    From: aperson@example.com
+    Subject: Test message 1
+    To: xtest@example.com
+    Message-ID: ...
+    <BLANKLINE>
+    Here is message 1
+    <BLANKLINE>
+    ------------------------------
+    <BLANKLINE>
+    From: aperson@example.com
+    Subject: Test message 2
+    To: xtest@example.com
+    Message-ID: ...
+    <BLANKLINE>
+    Here is message 2
+    <BLANKLINE>
+    ------------------------------
+    <BLANKLINE>
+    From: aperson@example.com
+    Subject: Test message 3
+    To: xtest@example.com
+    Message-ID: ...
+    <BLANKLINE>
+    Here is message 3
+    <BLANKLINE>
+    ------------------------------
+    <BLANKLINE>
+    From: aperson@example.com
+    Subject: Test message 4
+    To: xtest@example.com
+    Message-ID: ...
+    <BLANKLINE>
+    Here is message 4
+    <BLANKLINE>
+    ------------------------------
+    <BLANKLINE>
+    _______________________________________________
+    Test mailing list
+    test@example.com
+    http://lists.example.com/listinfo/test@example.com
+    <BLANKLINE>
+    <BLANKLINE>
+    End of Test Digest, Vol 1, Issue 1
+    **********************************
+    <BLANKLINE>
+
+
+Internationalized digests
+-------------------------
+
+When messages come in with a content-type character set different than that of
+the list's preferred language, recipients will get an internationalized
+digest.  French is not enabled by default site-wide, so enable that now.
+
+    >>> config.languages.enable_language('fr')
+
+    # Simulate the site administrator setting the default server language to
+    # French in the configuration file.  Without this, the English template
+    # will be found and the masthead won't be translated.
+    >>> config.push('french', """
+    ... [mailman]
+    ... default_language: fr
+    ... """)
+
+    >>> mlist.preferred_language = u'fr'
+    >>> msg = message_from_string("""\
+    ... From: aperson@example.org
+    ... To: test@example.com
+    ... Subject: =?iso-2022-jp?b?GyRCMGxIVhsoQg==?=
+    ... MIME-Version: 1.0
+    ... Content-Type: text/plain; charset=iso-2022-jp
+    ... Content-Transfer-Encoding: 7bit
+    ...
+    ... \x1b$B0lHV\x1b(B
+    ... """)
+
+Set the digest threshold to zero so that the digests will be sent immediately.
+
+    >>> mlist.digest_size_threshold = 0
+    >>> process(mlist, msg, {})
+
+The marker message is sitting in the digest queue.
+
+    >>> len(digestq.files)
+    1
+    >>> entry = get_queue_messages('digest')[0]
+    >>> dump_msgdata(entry.msgdata)
+    _parsemsg    : False
+    digest_number: 2
+    digest_path  : .../lists/test@example.com/digest.1.2.mmdf
+    listname     : test@example.com
+    version      : 3
+    volume       : 1
+
+The digest queue runner runs a loop, placing the two digests into the virgin
+queue.
+
+    # Put the messages back in the queue for the runner to handle.
+    >>> filebase = digestq.enqueue(entry.msg, entry.msgdata)
+    >>> runner.run()
+    >>> messages = get_queue_messages('virgin')
+    >>> len(messages)
+    2
+
+One of which is the MIME digest and the other of which is the RFC 1153 digest.
+
+    >>> if messages[0].msg.is_multipart():
+    ...     mime = messages[0].msg
+    ...     rfc1153 = messages[1].msg
+    ... else:
+    ...     mime = messages[1].msg
+    ...     rfc1153 = messages[0].msg
+
+You can see that the digests contain a mix of French and Japanese.
+
+    >>> print mime.as_string()
+    Content-Type: multipart/mixed; boundary="===============...=="
+    MIME-Version: 1.0
+    From: test-request@example.com
+    Subject: Groupe Test, Vol. 1, Parution 2
+    To: test@example.com
+    Reply-To: test@example.com
+    Date: ...
+    Message-ID: ...
+    <BLANKLINE>
+    --===============...==
+    Content-Type: text/plain; charset="iso-8859-1"
+    MIME-Version: 1.0
+    Content-Transfer-Encoding: quoted-printable
+    Content-Description: Groupe Test, Vol. 1, Parution 2
+    <BLANKLINE>
+    Envoyez vos messages pour la liste Test =E0
+    	test@example.com
+    <BLANKLINE>
+    Pour vous (d=E9s)abonner par le web, consultez
+    	http://lists.example.com/listinfo/test@example.com
+    <BLANKLINE>
+    ou, par courriel, envoyez un message avec =AB=A0help=A0=BB dans le corps ou
+    dans le sujet =E0
+    	test-request@example.com
+    <BLANKLINE>
+    Vous pouvez contacter l'administrateur de la liste =E0 l'adresse
+    	test-owner@example.com
+    <BLANKLINE>
+    Si vous r=E9pondez, n'oubliez pas de changer l'objet du message afin
+    qu'il soit plus sp=E9cifique que =AB=A0Re: Contenu du groupe de Test...=A0=
+    =BB
+    --===============...==
+    Content-Type: text/plain; charset="utf-8"
+    MIME-Version: 1.0
+    Content-Transfer-Encoding: base64
+    Content-Description: Today's Topics (1 messages)
+    <BLANKLINE>
+    VGjDqG1lcyBkdSBqb3VyIDoKCiAgIDEuIOS4gOeVqiAoYXBlcnNvbkBleGFtcGxlLm9yZykK
+    <BLANKLINE>
+    --===============...==
+    Content-Type: message/rfc822
+    MIME-Version: 1.0
+    <BLANKLINE>
+    From: aperson@example.org
+    To: test@example.com
+    Subject: =?iso-2022-jp?b?GyRCMGxIVhsoQg==?=
+    MIME-Version: 1.0
+    Content-Type: text/plain; charset=iso-2022-jp
+    Content-Transfer-Encoding: 7bit
+    <BLANKLINE>
+    一番
+    <BLANKLINE>
+    --===============...==
+    Content-Type: text/plain; charset="iso-8859-1"
+    MIME-Version: 1.0
+    Content-Transfer-Encoding: quoted-printable
+    Content-Description: =?utf-8?q?Pied_de_page_des_remises_group=C3=A9es?=
+    <BLANKLINE>
+    _______________________________________________
+    Test mailing list
+    test@example.com
+    http://lists.example.com/listinfo/test@example.com
+    <BLANKLINE>
+    --===============...==--
+
+The RFC 1153 digest will be encoded in UTF-8 since it contains a mixture of
+French and Japanese characters.
+
+    >>> print rfc1153.as_string()
+    From: test-request@example.com
+    Subject: Groupe Test, Vol. 1, Parution 2
+    To: test@example.com
+    Reply-To: test@example.com
+    Date: ...
+    Message-ID: ...
+    MIME-Version: 1.0
+    Content-Type: text/plain; charset="utf-8"
+    Content-Transfer-Encoding: base64
+    <BLANKLINE>
+    RW52b...
+    Y29tC...
+    Ly9sa...
+    dXJya...
+    cyBvd...
+    dmV6I...
+    dGVzd...
+    ZGUgY...
+    Zmlxd...
+    ZXMgZ...
+    LS0tL...
+    LS0tL...
+    c3RAZ...
+    d2RvZ...
+    LWpwC...
+    X19fX...
+    dEBle...
+    cGxlL...
+    KioqK...
+    <BLANKLINE>
+
+The content can be decoded to see the actual digest text.
+
+    # We must display the repr of the decoded value because doctests cannot
+    # handle the non-ascii characters.
+    >>> [repr(line) for line in rfc1153.get_payload(decode=True).splitlines()]
+    ["'Envoyez vos messages pour la liste Test \\xc3\\xa0'",
+     "'\\ttest@example.com'",
+     "''",
+     "'Pour vous (d\\xc3\\xa9s)abonner par le web, consultez'",
+     "'\\thttp://lists.example.com/listinfo/test@example.com'",
+     "''",
+     "'ou, par courriel, envoyez un message avec \\xc2\\xab\\xc2\\xa0...
+     "'dans le sujet \\xc3\\xa0'",
+     "'\\ttest-request@example.com'",
+     "''",
+     '"Vous pouvez contacter l\'administrateur de la liste \\xc3\\xa0 ...
+     "'\\ttest-owner@example.com'",
+     "''",
+     '"Si vous r\\xc3\\xa9pondez, n\'oubliez pas de changer l\'objet du ...
+     '"qu\'il soit plus sp\\xc3\\xa9cifique que \\xc2\\xab\\xc2\\xa0Re: ...
+     "''",
+     "'Th\\xc3\\xa8mes du jour :'",
+     "''",
+     "'   1. \\xe4\\xb8\\x80\\xe7\\x95\\xaa (aperson@example.org)'",
+     "''",
+     "''",
+     "'---------------------------------------------------------------------...
+     "''",
+     "'From: aperson@example.org'",
+     "'Subject: \\xe4\\xb8\\x80\\xe7\\x95\\xaa'",
+     "'To: test@example.com'",
+     "'Message-ID: ...
+     "'Content-Type: text/plain; charset=iso-2022-jp'",
+     "''",
+     "'\\xe4\\xb8\\x80\\xe7\\x95\\xaa'",
+     "''",
+     "'------------------------------'",
+     "''",
+     "'_______________________________________________'",
+     "'Test mailing list'",
+     "'test@example.com'",
+     "'http://lists.example.com/listinfo/test@example.com'",
+     "''",
+     "''",
+     "'Fin de Groupe Test, Vol. 1, Parution 2'",
+     "'**************************************'"]
diff --git a/src/mailman/queue/incoming.py b/src/mailman/queue/incoming.py
index 1adda6629..877255662 100644
--- a/src/mailman/queue/incoming.py
+++ b/src/mailman/queue/incoming.py
@@ -26,6 +26,14 @@ prepared for delivery.  Rejections, discards, and holds are processed
 immediately.
 """
 
+from __future__ import absolute_import, unicode_literals
+
+__metaclass__ = type
+__all__ = [
+    'IncomingRunner',
+    ]
+
+
 from mailman.core.chains import process
 from mailman.queue import Runner
 
@@ -35,6 +43,7 @@ class IncomingRunner(Runner):
     """The incoming queue runner."""
 
     def _dispose(self, mlist, msg, msgdata):
+        """See `IRunner`."""
         if msgdata.get('envsender') is None:
             msgdata['envsender'] = mlist.no_reply_address
         # Process the message through the mailing list's start chain.
diff --git a/src/mailman/queue/retry.py b/src/mailman/queue/retry.py
index 2b5a6afad..d2ca78add 100644
--- a/src/mailman/queue/retry.py
+++ b/src/mailman/queue/retry.py
@@ -15,6 +15,16 @@
 # You should have received a copy of the GNU General Public License along with
 # GNU Mailman.  If not, see <http://www.gnu.org/licenses/>.
 
+"""Retry delivery."""
+
+from __future__ import absolute_import, unicode_literals
+
+__metaclass__ = type
+__all__ = [
+    'RetryRunner',
+    ]
+
+
 import time
 
 from mailman.config import config
@@ -23,15 +33,13 @@ from mailman.queue import Runner
 
 
 class RetryRunner(Runner):
-    def __init__(self, slice=None, numslices=1):
-        Runner.__init__(self, slice, numslices)
-        self._outq = config.switchboards['out']
+    """Retry delivery."""
 
     def _dispose(self, mlist, msg, msgdata):
-        # Move it to the out queue for another retry
-        self._outq.enqueue(msg, msgdata)
+        # Move the message to the out queue for another try.
+        config.switchboards['outgoing'].enqueue(msg, msgdata)
         return False
 
     def _snooze(self, filecnt):
-        # We always want to snooze
+        # We always want to snooze.
         time.sleep(self.sleep_float)