28 files changed, 98 insertions, 248 deletions

diff --git a/src/mailman/handlers/acknowledge.py b/src/mailman/handlers/acknowledge.py
index db56c5806..809711426 100644
--- a/src/mailman/handlers/acknowledge.py
+++ b/src/mailman/handlers/acknowledge.py
@@ -20,11 +20,7 @@
 This only happens if the sender has set their AcknowledgePosts attribute.
 """
 
-__all__ = [
-    'Acknowledge',
-    ]
-
-
+from mailman import public
 from mailman.core.i18n import _
 from mailman.email.message import UserNotification
 from mailman.interfaces.handler import IHandler
@@ -35,7 +31,7 @@ from zope.component import getUtility
 from zope.interface import implementer
 
 
-
+@public
 @implementer(IHandler)
 class Acknowledge:
     """Send an acknowledgment."""
diff --git a/src/mailman/handlers/after_delivery.py b/src/mailman/handlers/after_delivery.py
index 8c4376338..efe38ec63 100644
--- a/src/mailman/handlers/after_delivery.py
+++ b/src/mailman/handlers/after_delivery.py
@@ -17,18 +17,14 @@
 
 """Perform some bookkeeping after a successful post."""
 
-__all__ = [
-    'AfterDelivery',
-    ]
-
-
+from mailman import public
 from mailman.core.i18n import _
 from mailman.interfaces.handler import IHandler
 from mailman.utilities.datetime import now
 from zope.interface import implementer
 
 
-
+@public
 @implementer(IHandler)
 class AfterDelivery:
     """Perform some bookkeeping after a successful post."""
diff --git a/src/mailman/handlers/avoid_duplicates.py b/src/mailman/handlers/avoid_duplicates.py
index 139b2545f..59cb568de 100644
--- a/src/mailman/handlers/avoid_duplicates.py
+++ b/src/mailman/handlers/avoid_duplicates.py
@@ -23,12 +23,8 @@ has already received a copy, we either drop the message, add a duplicate
 warning header, or pass it through, depending on the user's preferences.
 """
 
-__all__ = [
-    'AvoidDuplicates',
-    ]
-
-
 from email.utils import getaddresses, formataddr
+from mailman import public
 from mailman.core.i18n import _
 from mailman.interfaces.handler import IHandler
 from zope.interface import implementer
@@ -37,7 +33,7 @@ from zope.interface import implementer
 COMMASPACE = ', '
 
 
-
+@public
 @implementer(IHandler)
 class AvoidDuplicates:
     """If the user wishes it, do not send duplicates of the same message."""
diff --git a/src/mailman/handlers/cleanse.py b/src/mailman/handlers/cleanse.py
index 4a8aac850..56add9ef7 100644
--- a/src/mailman/handlers/cleanse.py
+++ b/src/mailman/handlers/cleanse.py
@@ -17,14 +17,10 @@
 
 """Cleanse certain headers from all messages."""
 
-__all__ = [
-    'Cleanse',
-    ]
-
-
 import logging
 
 from email.utils import formataddr
+from mailman import public
 from mailman.core.i18n import _
 from mailman.handlers.cook_headers import uheader
 from mailman.interfaces.handler import IHandler
@@ -34,7 +30,7 @@ from zope.interface import implementer
 log = logging.getLogger('mailman.post')
 
 
-
+@public
 @implementer(IHandler)
 class Cleanse:
     """Cleanse certain headers from all messages."""
diff --git a/src/mailman/handlers/cleanse_dkim.py b/src/mailman/handlers/cleanse_dkim.py
index 41041b358..72a9c5e81 100644
--- a/src/mailman/handlers/cleanse_dkim.py
+++ b/src/mailman/handlers/cleanse_dkim.py
@@ -25,19 +25,15 @@ and it will also give the MTA the opportunity to regenerate valid keys
 originating at the Mailman server for the outgoing message.
 """
 
-__all__ = [
-    'CleanseDKIM',
-    ]
-
-
 from lazr.config import as_boolean
+from mailman import public
 from mailman.config import config
 from mailman.core.i18n import _
 from mailman.interfaces.handler import IHandler
 from zope.interface import implementer
 
 
-
+@public
 @implementer(IHandler)
 class CleanseDKIM:
     """Remove DomainKeys headers."""
diff --git a/src/mailman/handlers/cook_headers.py b/src/mailman/handlers/cook_headers.py
index e49c2fa52..ed4c28c8c 100644
--- a/src/mailman/handlers/cook_headers.py
+++ b/src/mailman/handlers/cook_headers.py
@@ -17,15 +17,11 @@
 
 """Cook a message's headers."""
 
-__all__ = [
-    'CookHeaders',
-    ]
-
-
 import re
 
 from email.header import Header
 from email.utils import parseaddr, formataddr, getaddresses
+from mailman import public
 from mailman.core.i18n import _
 from mailman.interfaces.handler import IHandler
 from mailman.interfaces.mailinglist import Personalization, ReplyToMunging
@@ -38,7 +34,7 @@ MAXLINELEN = 78
 NONASCII = re.compile('[^\s!-~]')
 
 
-
+@public
 def uheader(mlist, s, header_name=None, continuation_ws='\t', maxlinelen=None):
     """Get the charset to encode the string in.
 
@@ -58,7 +54,6 @@ def uheader(mlist, s, header_name=None, continuation_ws='\t', maxlinelen=None):
     return Header(s, charset, maxlinelen, header_name, continuation_ws)
 
 
-
 def process(mlist, msg, msgdata):
     """Process the headers of the message."""
     # Set the "X-Ack: no" header if noack flag is set.
@@ -103,7 +98,7 @@ def process(mlist, msg, msgdata):
         # A convenience function, requires nested scopes.  pair is (name, addr)
         new = []
         d = {}
-        def add(pair):
+        def add(pair):                              # flake8: noqa
             lcaddr = pair[1].lower()
             if lcaddr in d:
                 return
@@ -143,8 +138,9 @@ def process(mlist, msg, msgdata):
         # Also skip Cc if this is an anonymous list as list posting address
         # is already in From and Reply-To in this case.
         if (mlist.personalize is Personalization.full and
-            mlist.reply_goes_to_list is not ReplyToMunging.point_to_list and
-            not mlist.anonymous_list):
+                mlist.reply_goes_to_list is not
+                    ReplyToMunging.point_to_list and
+                not mlist.anonymous_list):
             # Watch out for existing Cc headers, merge, and remove dups.  Note
             # that RFC 2822 says only zero or one Cc header is allowed.
             new = []
@@ -157,7 +153,7 @@ def process(mlist, msg, msgdata):
             msg['Cc'] = COMMASPACE.join([formataddr(pair) for pair in new])
 
 
-
+@public
 @implementer(IHandler)
 class CookHeaders:
     """Modify message headers."""
diff --git a/src/mailman/handlers/decorate.py b/src/mailman/handlers/decorate.py
index b8cdcb9ae..186c86a6d 100644
--- a/src/mailman/handlers/decorate.py
+++ b/src/mailman/handlers/decorate.py
@@ -17,17 +17,11 @@
 
 """Decorate a message by sticking the header and footer around it."""
 
-__all__ = [
-    'Decorate',
-    'decorate',
-    'decorate_template',
-    ]
-
-
 import re
 import logging
 
 from email.mime.text import MIMEText
+from mailman import public
 from mailman.core.i18n import _
 from mailman.email.message import Message
 from mailman.interfaces.handler import IHandler
@@ -43,7 +37,6 @@ log = logging.getLogger('mailman.error')
 alog = logging.getLogger('mailman.archiver')
 
 
-
 def process(mlist, msg, msgdata):
     """Decorate the message with headers and footers."""
     # Digests and Mailman-craft messages should not get additional headers.
@@ -216,7 +209,7 @@ def process(mlist, msg, msgdata):
     msg['Content-Type'] = 'multipart/mixed'
 
 
-
+@public
 def decorate(mlist, uri, extradict=None):
     """Expand the decoration template from its URI."""
     if uri is None:
@@ -232,22 +225,25 @@ def decorate(mlist, uri, extradict=None):
     return decorate_template(mlist, template, extradict)
 
 
-
+@public
 def decorate_template(mlist, template, extradict=None):
     """Expand the decoration template."""
     # Create a dictionary which includes the default set of interpolation
     # variables allowed in headers and footers.  These will be augmented by
     # any key/value pairs in the extradict.
-    substitutions = dict(
-        fqdn_listname = mlist.fqdn_listname,
-        list_name     = mlist.list_name,
-        host_name     = mlist.mail_host,
-        display_name  = mlist.display_name,
-        listinfo_uri  = mlist.script_url('listinfo'),
-        list_requests = mlist.request_address,
-        description   = mlist.description,
-        info          = mlist.info,
-        )
+    substitutions = {
+        key: getattr(mlist, key)
+        for key in ('fqdn_listname',
+                    'list_name',
+                    'mail_host',
+                    'display_name',
+                    'request_address',
+                    'description',
+                    'info',
+                    )
+        }
+    # This must eventually go away.
+    substitutions['listinfo_uri'] = mlist.script_url('listinfo')
     if extradict is not None:
         substitutions.update(extradict)
     text = expand(template, substitutions)
@@ -255,7 +251,7 @@ def decorate_template(mlist, template, extradict=None):
     return re.sub(r' *\r?\n', r'\n', text)
 
 
-
+@public
 @implementer(IHandler)
 class Decorate:
     """Decorate a message with headers and footers."""
diff --git a/src/mailman/handlers/file_recipients.py b/src/mailman/handlers/file_recipients.py
index 7e4d07bd4..95160706a 100644
--- a/src/mailman/handlers/file_recipients.py
+++ b/src/mailman/handlers/file_recipients.py
@@ -17,20 +17,16 @@
 
 """Get the normal delivery recipients from a Sendmail style :include: file."""
 
-__all__ = [
-    'FileRecipients',
-    ]
-
-
 import os
 import errno
 
+from mailman import public
 from mailman.core.i18n import _
 from mailman.interfaces.handler import IHandler
 from zope.interface import implementer
 
 
-
+@public
 @implementer(IHandler)
 class FileRecipients:
     """Get the normal delivery recipients from an include file."""
diff --git a/src/mailman/handlers/member_recipients.py b/src/mailman/handlers/member_recipients.py
index 6a28af11a..ffcecfb18 100644
--- a/src/mailman/handlers/member_recipients.py
+++ b/src/mailman/handlers/member_recipients.py
@@ -23,11 +23,7 @@ on the `recipients' attribute of the message.  This attribute is used by the
 SendmailDeliver and BulkDeliver modules.
 """
 
-__all__ = [
-    'MemberRecipients',
-    ]
-
-
+from mailman import public
 from mailman.config import config
 from mailman.core.i18n import _
 from mailman.interfaces.handler import IHandler
@@ -37,7 +33,7 @@ from mailman.utilities.string import wrap
 from zope.interface import implementer
 
 
-
+@public
 @implementer(IHandler)
 class MemberRecipients:
     """Calculate the regular (i.e. non-digest) recipients of the message."""
@@ -92,12 +88,13 @@ for delivery.  The original message as received by Mailman is attached.
             recipients.remove(member.address.email)
         # Handle topic classifications
         # XXX: Disabled for now until we fix it properly
-        #do_topic_filters(mlist, msg, msgdata, recipients)
+        #
+        # do_topic_filters(mlist, msg, msgdata, recipients)
+        #
         # Bookkeeping
         msgdata['recipients'] = recipients
 
 
-
 def do_topic_filters(mlist, msg, msgdata, recipients):
     """Filter out recipients based on topics."""
     if not mlist.topics_enabled:
@@ -135,7 +132,7 @@ def do_topic_filters(mlist, msg, msgdata, recipients):
                 # this message by default.
                 continue
             if not mlist.getMemberOption(
-                user, config.ReceiveNonmatchingTopics):
+                    user, config.ReceiveNonmatchingTopics):
                 # The user has interest in some topics, but elects not to
                 # receive message that match no topics, so zap him.
                 zap_recipients.append(user)
diff --git a/src/mailman/handlers/mime_delete.py b/src/mailman/handlers/mime_delete.py
index a1e861bf8..267cb227a 100644
--- a/src/mailman/handlers/mime_delete.py
+++ b/src/mailman/handlers/mime_delete.py
@@ -24,11 +24,6 @@ wrapping only single sections after other processing are replaced by their
 contents.
 """
 
-__all__ = [
-    'MIMEDelete',
-    ]
-
-
 import os
 import shutil
 import logging
@@ -41,6 +36,7 @@ from email.mime.message import MIMEMessage
 from email.mime.text import MIMEText
 from itertools import count
 from lazr.config import as_boolean
+from mailman import public
 from mailman.config import config
 from mailman.core.i18n import _
 from mailman.email.message import OwnerNotification
@@ -56,21 +52,20 @@ from zope.interface import implementer
 log = logging.getLogger('mailman.error')
 
 
-
 def dispose(mlist, msg, msgdata, why):
     if mlist.filter_action is FilterAction.reject:
         # Bounce the message to the original author.
         raise RejectMessage(why)
     elif mlist.filter_action is FilterAction.forward:
         # Forward it on to the list moderators.
-        text=_("""\
+        text = _("""\
 The attached message matched the $mlist.display_name mailing list's content
 filtering rules and was prevented from being forwarded on to the list
 membership.  You are receiving the only remaining copy of the discarded
 message.
 
 """)
-        subject=_('Content filter message notification')
+        subject = _('Content filter message notification')
         notice = OwnerNotification(mlist, subject, roster=mlist.moderators)
         notice.set_type('multipart/mixed')
         notice.attach(MIMEText(text))
@@ -83,17 +78,16 @@ message.
             # placed in the 'bad' queue should the site administrator want to
             # inspect the message.
             filebase = config.switchboards['bad'].enqueue(msg, msgdata)
-            log.info('{0} preserved in file base {1}'.format(
+            log.info('{} preserved in file base {}'.format(
                 msg.get('message-id', 'n/a'), filebase))
     else:
         log.error(
-            '{1} invalid FilterAction: {0}.  Treating as discard'.format(
+            '{} invalid FilterAction: {}.  Treating as discard'.format(
                 mlist.fqdn_listname, mlist.filter_action.name))
     # Most cases also discard the message
     raise DiscardMessage(why)
 
 
-
 def process(mlist, msg, msgdata):
     # We also don't care about our own digests or plaintext
     ctype = msg.get_content_type()
@@ -115,11 +109,13 @@ def process(mlist, msg, msgdata):
     fext = get_file_ext(msg)
     if fext:
         if fext in filterexts:
-            dispose(mlist, msg, msgdata,
-                 _("The message's file extension was explicitly disallowed"))
+            dispose(
+                mlist, msg, msgdata,
+                _("The message's file extension was explicitly disallowed"))
         if passexts and not (fext in passexts):
-            dispose(mlist, msg, msgdata,
-                 _("The message's file extension was not explicitly allowed"))
+            dispose(
+                mlist, msg, msgdata,
+                _("The message's file extension was not explicitly allowed"))
     numparts = len([subpart for subpart in msg.walk()])
     # If the message is a multipart, filter out matching subparts
     if msg.is_multipart():
@@ -158,10 +154,9 @@ def process(mlist, msg, msgdata):
             reset_payload(msg, useful)
             changedp = 1
     if changedp:
-        msg['X-Content-Filtered-By'] = 'Mailman/MimeDel {0}'.format(VERSION)
+        msg['X-Content-Filtered-By'] = 'Mailman/MimeDel {}'.format(VERSION)
 
 
-
 def reset_payload(msg, subpart):
     # Reset payload of msg to contents of subpart, and fix up content headers
     payload = subpart.get_payload()
@@ -182,7 +177,6 @@ def reset_payload(msg, subpart):
         msg['Content-Description'] = cdesc
 
 
-
 def filter_parts(msg, filtertypes, passtypes, filterexts, passexts):
     # Look at all the message's subparts, and recursively filter
     if not msg.is_multipart():
@@ -220,7 +214,6 @@ def filter_parts(msg, filtertypes, passtypes, filterexts, passexts):
     return True
 
 
-
 def collapse_multipart_alternatives(msg):
     if not msg.is_multipart():
         return
@@ -237,7 +230,6 @@ def collapse_multipart_alternatives(msg):
     msg.set_payload(newpayload)
 
 
-
 def to_plaintext(msg):
     changedp = 0
     counter = count()
@@ -265,7 +257,6 @@ def to_plaintext(msg):
     return changedp
 
 
-
 def get_file_ext(m):
     """
     Get filename extension. Caution: some virus don't put filename
@@ -274,7 +265,7 @@ def get_file_ext(m):
     fext = ''
     filename = m.get_filename('') or m.get_param('name', '')
     if filename:
-        fext = os.path.splitext(oneline(filename,'utf-8'))[1]
+        fext = os.path.splitext(oneline(filename, 'utf-8'))[1]
         if len(fext) > 1:
             fext = fext[1:]
         else:
@@ -282,7 +273,7 @@ def get_file_ext(m):
     return fext
 
 
-
+@public
 @implementer(IHandler)
 class MIMEDelete:
     """Filter the MIME content of messages."""
diff --git a/src/mailman/handlers/owner_recipients.py b/src/mailman/handlers/owner_recipients.py
index 9a18f1ceb..9ef2568f5 100644
--- a/src/mailman/handlers/owner_recipients.py
+++ b/src/mailman/handlers/owner_recipients.py
@@ -17,11 +17,7 @@
 
 """Calculate the list owner recipients (includes moderators)."""
 
-__all__ = [
-    'OwnerRecipients',
-    ]
-
-
+from mailman import public
 from mailman.config import config
 from mailman.core.i18n import _
 from mailman.interfaces.handler import IHandler
@@ -29,7 +25,7 @@ from mailman.interfaces.member import DeliveryStatus
 from zope.interface import implementer
 
 
-
+@public
 @implementer(IHandler)
 class OwnerRecipients:
     """Calculate the owner (and moderator) recipients for -owner postings."""
diff --git a/src/mailman/handlers/replybot.py b/src/mailman/handlers/replybot.py
index 0302d2793..546bb1ec4 100644
--- a/src/mailman/handlers/replybot.py
+++ b/src/mailman/handlers/replybot.py
@@ -17,13 +17,9 @@
 
 """Handler for automatic responses."""
 
-__all__ = [
-    'Replybot',
-    ]
-
-
 import logging
 
+from mailman import public
 from mailman.core.i18n import _
 from mailman.email.message import UserNotification
 from mailman.interfaces.autorespond import (
@@ -39,7 +35,7 @@ from zope.interface import implementer
 log = logging.getLogger('mailman.error')
 
 
-
+@public
 @implementer(IHandler)
 class Replybot:
     """Send automatic responses."""
@@ -101,12 +97,13 @@ class Replybot:
             'Auto-response for your message to the "$display_name" '
             'mailing list')
         # Do string interpolation into the autoresponse text
-        d = dict(list_name = mlist.list_name,
-                 display_name = display_name,
-                 listurl = mlist.script_url('listinfo'),
-                 requestemail = mlist.request_address,
-                 owneremail = mlist.owner_address,
-                 )
+        d = dict(
+            list_name=mlist.list_name,
+            display_name=display_name,
+            listurl=mlist.script_url('listinfo'),
+            requestemail=mlist.request_address,
+            owneremail=mlist.owner_address,
+            )
         # Interpolation and Wrap the response text.
         text = wrap(expand(response_text, d))
         outmsg = UserNotification(msg.sender, mlist.bounces_address,
diff --git a/src/mailman/handlers/rfc_2369.py b/src/mailman/handlers/rfc_2369.py
index 4f172bde1..3daf6414d 100644
--- a/src/mailman/handlers/rfc_2369.py
+++ b/src/mailman/handlers/rfc_2369.py
@@ -17,14 +17,10 @@
 
 """RFC 2369 List-* and related headers."""
 
-__all__ = [
-    'RFC2369',
-    ]
-
-
 import logging
 
 from email.utils import formataddr
+from mailman import public
 from mailman.core.i18n import _
 from mailman.handlers.cook_headers import uheader
 from mailman.interfaces.archiver import ArchivePolicy
@@ -38,7 +34,6 @@ CONTINUATION = ',\n\t'
 log = logging.getLogger('mailman.archiver')
 
 
-
 def process(mlist, msg, msgdata):
     """Add the RFC 2369 List-* and related headers."""
     # Some people really hate the List-* headers.  It seems that the free
@@ -126,7 +121,7 @@ def process(mlist, msg, msgdata):
         msg[h] = v
 
 
-
+@public
 @implementer(IHandler)
 class RFC2369:
     """Add the RFC 2369 List-* headers."""
diff --git a/src/mailman/handlers/subject_prefix.py b/src/mailman/handlers/subject_prefix.py
index c3490986c..8a9da8b42 100644
--- a/src/mailman/handlers/subject_prefix.py
+++ b/src/mailman/handlers/subject_prefix.py
@@ -17,14 +17,10 @@
 
 """Subject header prefix munging."""
 
-__all__ = [
-    'SubjectPrefix',
-    ]
-
-
 import re
 
 from email.header import Header, make_header, decode_header
+from mailman import public
 from mailman.core.i18n import _
 from mailman.interfaces.handler import IHandler
 from zope.interface import implementer
@@ -35,7 +31,6 @@ ASCII_CHARSETS = (None, 'ascii', 'us-ascii')
 EMPTYSTRING = ''
 
 
-
 def ascii_header(mlist, msgdata, subject, prefix, prefix_pattern, ws):
     if mlist.preferred_language.charset not in ASCII_CHARSETS:
         return None
@@ -127,7 +122,7 @@ def mixed_charsets(mlist, msgdata, subject, prefix, prefix_pattern, ws):
     return make_header(chunks, continuation_ws=ws)
 
 
-
+@public
 @implementer(IHandler)
 class SubjectPrefix:
     """Add a list-specific prefix to the Subject header value."""
diff --git a/src/mailman/handlers/tagger.py b/src/mailman/handlers/tagger.py
index 50112c74f..fb0a24ba5 100644
--- a/src/mailman/handlers/tagger.py
+++ b/src/mailman/handlers/tagger.py
@@ -17,15 +17,11 @@
 
 """Extract topics from the original mail message."""
 
-__all__ = [
-    'Tagger',
-    ]
-
-
 import re
 import email.iterators
 import email.parser
 
+from mailman import public
 from mailman.core.i18n import _
 from mailman.interfaces.handler import IHandler
 from zope.interface import implementer
@@ -37,7 +33,6 @@ EMPTYSTRING = ''
 NLTAB = '\n\t'
 
 
-
 def process(mlist, msg, msgdata):
     """Tag the message for topics."""
     if not mlist.topics_enabled:
@@ -75,7 +70,6 @@ def process(mlist, msg, msgdata):
         msg['X-Topics'] = NLTAB.join(sorted(hits))
 
 
-
 def scanbody(msg, numlines=None):
     """Scan the body for keywords."""
     # We only scan the body of the message if it is of MIME type text/plain,
@@ -84,8 +78,8 @@ def scanbody(msg, numlines=None):
     found = None
     if msg.get_content_type() == 'text/plain':
         found = msg
-    elif msg.is_multipart()\
-         and msg.get_content_type() == 'multipart/alternative':
+    elif (msg.is_multipart() and
+            msg.get_content_type() == 'multipart/alternative'):
         for found in msg.get_payload():
             if found.get_content_type() == 'text/plain':
                 break
@@ -115,7 +109,6 @@ def scanbody(msg, numlines=None):
     return msg.get_all('subject', []) + msg.get_all('keywords', [])
 
 
-
 class _ForgivingParser(email.parser.HeaderParser):
     """An lax email parser.
 
@@ -173,7 +166,7 @@ class _ForgivingParser(email.parser.HeaderParser):
             container[lastheader] = NLTAB.join(lastvalue)
 
 
-
+@public
 @implementer(IHandler)
 class Tagger:
     """Tag messages with topic matches."""
diff --git a/src/mailman/handlers/tests/test_cook_headers.py b/src/mailman/handlers/tests/test_cook_headers.py
index e68f6a23d..fad3f49d9 100644
--- a/src/mailman/handlers/tests/test_cook_headers.py
+++ b/src/mailman/handlers/tests/test_cook_headers.py
@@ -17,11 +17,6 @@
 
 """Test the cook_headers handler."""
 
-__all__ = [
-    'TestCookHeaders',
-    ]
-
-
 import unittest
 
 from mailman.app.lifecycle import create_list
@@ -32,7 +27,6 @@ from mailman.testing.helpers import (
 from mailman.testing.layers import ConfigLayer
 
 
-
 class TestCookHeaders(unittest.TestCase):
     """Test the cook_headers handler."""
 
@@ -49,11 +43,10 @@ class TestCookHeaders(unittest.TestCase):
         bart = subscribe(self._mlist, 'Bart')
         bart.preferences.delivery_mode = DeliveryMode.plaintext_digests
         make_digest_messages(self._mlist)
-        messages = [bag.msg for bag in get_queue_messages('virgin')]
-        self.assertEqual(len(messages), 2)
-        for msg in messages:
+        items = get_queue_messages('virgin', expected_count=2)
+        for item in items:
             try:
-                cook_headers.process(self._mlist, msg, {})
+                cook_headers.process(self._mlist, item.msg, {})
             except AttributeError as error:
                 # LP: #1130696 would raise an AttributeError on .sender
                 self.fail(error)
diff --git a/src/mailman/handlers/tests/test_decorate.py b/src/mailman/handlers/tests/test_decorate.py
index 2a44d4186..7d44214cb 100644
--- a/src/mailman/handlers/tests/test_decorate.py
+++ b/src/mailman/handlers/tests/test_decorate.py
@@ -17,12 +17,6 @@
 
 """Test the decorate handler."""
 
-__all__ = [
-    'TestBrokenPermalink',
-    'TestDecorate',
-    ]
-
-
 import os
 import unittest
 
@@ -37,7 +31,6 @@ from tempfile import TemporaryDirectory
 from zope.interface import implementer
 
 
-
 @implementer(IArchiver)
 class TestArchiver:
     """A test archiver"""
@@ -60,7 +53,6 @@ class BrokenArchiver:
         raise RuntimeError('Cannot get permalink')
 
 
-
 class TestDecorate(unittest.TestCase):
     """Test the cook_headers handler."""
 
diff --git a/src/mailman/handlers/tests/test_file_recips.py b/src/mailman/handlers/tests/test_file_recips.py
index f7072d850..ee3084288 100644
--- a/src/mailman/handlers/tests/test_file_recips.py
+++ b/src/mailman/handlers/tests/test_file_recips.py
@@ -17,11 +17,6 @@
 
 """Test file-recips handler."""
 
-__all__ = [
-    'TestFileRecips',
-    ]
-
-
 import os
 import unittest
 
@@ -31,7 +26,6 @@ from mailman.testing.helpers import specialized_message_from_string as mfs
 from mailman.testing.layers import ConfigLayer
 
 
-
 class TestFileRecips(unittest.TestCase):
     layer = ConfigLayer
 
diff --git a/src/mailman/handlers/tests/test_filter.py b/src/mailman/handlers/tests/test_filter.py
index 0933d8b00..7ee6249f0 100644
--- a/src/mailman/handlers/tests/test_filter.py
+++ b/src/mailman/handlers/tests/test_filter.py
@@ -17,11 +17,6 @@
 
 """Test the filter handler."""
 
-__all__ = [
-    'TestFilters',
-    ]
-
-
 import unittest
 
 from mailman.app.lifecycle import create_list
@@ -32,7 +27,6 @@ from mailman.testing.helpers import specialized_message_from_string as mfs
 from mailman.testing.layers import ConfigLayer
 
 
-
 class TestFilters(unittest.TestCase):
     layer = ConfigLayer
 
diff --git a/src/mailman/handlers/tests/test_mimedel.py b/src/mailman/handlers/tests/test_mimedel.py
index d5670f1bc..e685e24f3 100644
--- a/src/mailman/handlers/tests/test_mimedel.py
+++ b/src/mailman/handlers/tests/test_mimedel.py
@@ -17,13 +17,6 @@
 
 """Test the mime_delete handler."""
 
-__all__ = [
-    'TestDispose',
-    'TestHTMLFilter',
-    'dummy_script',
-    ]
-
-
 import os
 import sys
 import shutil
@@ -45,7 +38,6 @@ from mailman.testing.layers import ConfigLayer
 from zope.component import getUtility
 
 
-
 @contextmanager
 def dummy_script():
     with ExitStack() as resources:
@@ -66,7 +58,6 @@ html_to_plain_text_command = {exe} {script} $filename
         yield
 
 
-
 class TestDispose(unittest.TestCase):
     """Test the mime_delete handler."""
 
@@ -94,7 +85,7 @@ Message-ID: <ant>
             mime_delete.dispose(self._mlist, self._msg, {}, 'discarding')
         self.assertEqual(cm.exception.message, 'discarding')
         # There should be no messages in the 'bad' queue.
-        self.assertEqual(len(get_queue_messages('bad')), 0)
+        get_queue_messages('bad', expected_count=0)
 
     def test_dispose_bounce(self):
         self._mlist.filter_action = FilterAction.reject
@@ -102,7 +93,7 @@ Message-ID: <ant>
             mime_delete.dispose(self._mlist, self._msg, {}, 'rejecting')
         self.assertEqual(cm.exception.message, 'rejecting')
         # There should be no messages in the 'bad' queue.
-        self.assertEqual(len(get_queue_messages('bad')), 0)
+        get_queue_messages('bad', expected_count=0)
 
     def test_dispose_forward(self):
         # The disposed message gets forwarded to the list moderators.  So
@@ -119,9 +110,8 @@ Message-ID: <ant>
         self.assertEqual(cm.exception.message, 'forwarding')
         # There should now be a multipart message in the virgin queue destined
         # for the mailing list owners.
-        messages = get_queue_messages('virgin')
-        self.assertEqual(len(messages), 1)
-        message = messages[0].msg
+        items = get_queue_messages('virgin', expected_count=1)
+        message = items[0].msg
         self.assertEqual(message.get_content_type(), 'multipart/mixed')
         # Anne and Bart should be recipients of the message, but it will look
         # like the message is going to the list owners.
@@ -160,7 +150,7 @@ message.
             mime_delete.dispose(self._mlist, self._msg, {}, 'not preserved')
         self.assertEqual(cm.exception.message, 'not preserved')
         # There should be no messages in the 'bad' queue.
-        self.assertEqual(len(get_queue_messages('bad')), 0)
+        get_queue_messages('bad', expected_count=0)
 
     @configuration('mailman', filtered_messages_are_preservable='yes')
     def test_dispose_preservable(self):
@@ -173,9 +163,8 @@ message.
             mime_delete.dispose(self._mlist, self._msg, {}, 'preserved')
         self.assertEqual(cm.exception.message, 'preserved')
         # There should be no messages in the 'bad' queue.
-        messages = get_queue_messages('bad')
-        self.assertEqual(len(messages), 1)
-        message = messages[0].msg
+        items = get_queue_messages('bad', expected_count=1)
+        message = items[0].msg
         self.assertEqual(message['subject'], 'A disposable message')
         self.assertEqual(message['message-id'], '<ant>')
 
@@ -194,11 +183,10 @@ message.
             self.assertEqual(cm.exception.message, 'bad action')
             line = mark.readline()[:-1]
             self.assertTrue(line.endswith(
-                '{0} invalid FilterAction: test@example.com.  '
+                'test@example.com invalid FilterAction: {}.  '
                 'Treating as discard'.format(action.name)))
 
 
-
 class TestHTMLFilter(unittest.TestCase):
     """Test the conversion of HTML to plaintext."""
 
diff --git a/src/mailman/handlers/tests/test_recipients.py b/src/mailman/handlers/tests/test_recipients.py
index 5fb69c272..5a6ecf226 100644
--- a/src/mailman/handlers/tests/test_recipients.py
+++ b/src/mailman/handlers/tests/test_recipients.py
@@ -17,12 +17,6 @@
 
 """Testing various recipients stuff."""
 
-__all__ = [
-    'TestMemberRecipients',
-    'TestOwnerRecipients',
-    ]
-
-
 import unittest
 
 from mailman.app.lifecycle import create_list
@@ -35,7 +29,6 @@ from mailman.testing.layers import ConfigLayer
 from zope.component import getUtility
 
 
-
 class TestMemberRecipients(unittest.TestCase):
     """Test regular member recipient calculation."""
 
@@ -87,7 +80,6 @@ To: test@example.com
                                                      'dave@example.com')))
 
 
-
 class TestOwnerRecipients(unittest.TestCase):
     """Test owner recipient calculation."""
 
diff --git a/src/mailman/handlers/tests/test_rfc_2369.py b/src/mailman/handlers/tests/test_rfc_2369.py
index cbbaf2153..e78cf9c47 100644
--- a/src/mailman/handlers/tests/test_rfc_2369.py
+++ b/src/mailman/handlers/tests/test_rfc_2369.py
@@ -17,11 +17,6 @@
 
 """Test the rfc_2369 handler."""
 
-__all__ = [
-    'TestRFC2369',
-    ]
-
-
 import unittest
 
 from mailman.app.lifecycle import create_list
@@ -35,7 +30,6 @@ from urllib.parse import urljoin
 from zope.interface import implementer
 
 
-
 @implementer(IArchiver)
 class DummyArchiver:
     """An example archiver which does nothing but return URLs."""
@@ -74,7 +68,6 @@ class BrokenArchiver:
         raise RuntimeError('Cannot archive message')
 
 
-
 class TestRFC2369(unittest.TestCase):
     """Test the rfc_2369 handler."""
 
diff --git a/src/mailman/handlers/tests/test_subject_prefix.py b/src/mailman/handlers/tests/test_subject_prefix.py
index 91c799785..1680f4d2d 100644
--- a/src/mailman/handlers/tests/test_subject_prefix.py
+++ b/src/mailman/handlers/tests/test_subject_prefix.py
@@ -17,11 +17,6 @@
 
 """Test the Subject header prefix munging.."""
 
-__all__ = [
-    'TestSubjectPrefix',
-    ]
-
-
 import unittest
 
 from mailman.app.lifecycle import create_list
@@ -30,7 +25,6 @@ from mailman.email.message import Message
 from mailman.testing.layers import ConfigLayer
 
 
-
 class TestSubjectPrefix(unittest.TestCase):
     layer = ConfigLayer
 
@@ -120,7 +114,7 @@ class TestSubjectPrefix(unittest.TestCase):
         self._mlist.post_id = 456
         msg = Message()
         msg['Subject'] = \
-          '[Test 123] Re: =?iso-2022-jp?b?GyRCJWEhPCVrJV4lcxsoQg==?='
+            '[Test 123] Re: =?iso-2022-jp?b?GyRCJWEhPCVrJV4lcxsoQg==?='
         self._process(self._mlist, msg, {})
         subject = msg['subject']
         self.assertEqual(
diff --git a/src/mailman/handlers/tests/test_to_digest.py b/src/mailman/handlers/tests/test_to_digest.py
index 42a5cd65c..3ce12921e 100644
--- a/src/mailman/handlers/tests/test_to_digest.py
+++ b/src/mailman/handlers/tests/test_to_digest.py
@@ -17,11 +17,6 @@
 
 """Test the to_digest handler."""
 
-__all__ = [
-    'TestToDigest',
-    ]
-
-
 import os
 import unittest
 
@@ -31,7 +26,6 @@ from mailman.testing.helpers import specialized_message_from_string as mfs
 from mailman.testing.layers import ConfigLayer
 
 
-
 class TestToDigest(unittest.TestCase):
     """Test the to_digest handler."""
 
diff --git a/src/mailman/handlers/to_archive.py b/src/mailman/handlers/to_archive.py
index 4a388bdca..d5b980ab4 100644
--- a/src/mailman/handlers/to_archive.py
+++ b/src/mailman/handlers/to_archive.py
@@ -17,11 +17,7 @@
 
 """Add the message to the archives."""
 
-__all__ = [
-    'ToArchive',
-    ]
-
-
+from mailman import public
 from mailman.config import config
 from mailman.core.i18n import _
 from mailman.interfaces.archiver import ArchivePolicy
@@ -29,7 +25,7 @@ from mailman.interfaces.handler import IHandler
 from zope.interface import implementer
 
 
-
+@public
 @implementer(IHandler)
 class ToArchive:
     """Add the message to the archives."""
@@ -41,7 +37,7 @@ class ToArchive:
         """See `IHandler`."""
         # Short circuits.
         if (msgdata.get('isdigest') or
-            mlist.archive_policy is ArchivePolicy.never):
+                mlist.archive_policy is ArchivePolicy.never):
             return
         # Common practice seems to favor "X-No-Archive: yes".  No other value
         # for this header seems to make sense, so we'll just test for it's
diff --git a/src/mailman/handlers/to_digest.py b/src/mailman/handlers/to_digest.py
index 54679f47e..671a2197c 100644
--- a/src/mailman/handlers/to_digest.py
+++ b/src/mailman/handlers/to_digest.py
@@ -17,13 +17,9 @@
 
 """Add the message to the list's current digest."""
 
-__all__ = [
-    'ToDigest',
-    ]
-
-
 import os
 
+from mailman import public
 from mailman.app.digests import maybe_send_digest_now
 from mailman.core.i18n import _
 from mailman.interfaces.handler import IHandler
@@ -31,7 +27,7 @@ from mailman.utilities.mailbox import Mailbox
 from zope.interface import implementer
 
 
-
+@public
 @implementer(IHandler)
 class ToDigest:
     """Add the message to the digest, possibly sending it."""
diff --git a/src/mailman/handlers/to_outgoing.py b/src/mailman/handlers/to_outgoing.py
index 3e68016e3..b9fae912c 100644
--- a/src/mailman/handlers/to_outgoing.py
+++ b/src/mailman/handlers/to_outgoing.py
@@ -22,18 +22,14 @@ posted to the list membership.  Anything else that needs to go out to some
 recipient should just be placed in the out queue directly.
 """
 
-__all__ = [
-    'ToOutgoing',
-    ]
-
-
+from mailman import public
 from mailman.config import config
 from mailman.core.i18n import _
 from mailman.interfaces.handler import IHandler
 from zope.interface import implementer
 
 
-
+@public
 @implementer(IHandler)
 class ToOutgoing:
     """Send the message to the outgoing queue."""
diff --git a/src/mailman/handlers/to_usenet.py b/src/mailman/handlers/to_usenet.py
index a36248be4..4bfa00c5f 100644
--- a/src/mailman/handlers/to_usenet.py
+++ b/src/mailman/handlers/to_usenet.py
@@ -17,13 +17,9 @@
 
 """Move the message to the mail->news queue."""
 
-__all__ = [
-    'ToUsenet',
-    ]
-
-
 import logging
 
+from mailman import public
 from mailman.config import config
 from mailman.core.i18n import _
 from mailman.interfaces.handler import IHandler
@@ -34,7 +30,7 @@ COMMASPACE = ', '
 log = logging.getLogger('mailman.error')
 
 
-
+@public
 @implementer(IHandler)
 class ToUsenet:
     """Move the message to the outgoing news queue."""
@@ -46,8 +42,8 @@ class ToUsenet:
         """See `IHandler`."""
         # Short circuits.
         if (not mlist.gateway_to_news or
-            msgdata.get('isdigest') or
-            msgdata.get('fromusenet')):
+                msgdata.get('isdigest') or
+                msgdata.get('fromusenet')):
             # Short-circuit.
             return
         # Sanity checks.