Merge "docs: Switch a mailing list to default moderation"

doc/source/lists.rst

@@ -53,6 +53,61 @@ This may only be performed with root access to the list server.
 Use context help for the CLI's many subcommands, or see the Mailman v3
 documentation for more details.
 
+Example: Switch a mailing list to default moderation
+----------------------------------------------------
+
+For popular lists which allow subscribers to post freely and only
+moderate messages from non-subscribers, it's not uncommon to see
+spammers bypass this rule by subscribing first (or posting spam through
+Hyperkitty, as it auto-subscribes the poster). The recommended
+mitigation is to set the list's default action to hold for moderation,
+and then have a moderator switch any legitimate new subscriber's action
+to default processing after approving their post. For subscribers
+imported from Mailman 2.1, those typically already have default
+processing set, but anyone subscribing through Mailman 3 will use the
+list default (i.e. unset for their account) so we need to bulk update
+all of those to default processing or else they're going to be treated
+like new subscribers.
+
+Here's how to do that from an SSH session on the mailing list server
+(make sure to pass the actual list name in the ``-l`` option instead of
+``sample-list@lists.example.org``):
+
+.. code-block:: bash
+
+  $ sudo docker-compose -f /etc/mailman-compose/docker-compose.yaml exec -u mailman mailman-core mailman shell -l sample-list@lists.example.org -i
+
+  Welcome to the GNU Mailman shell
+  Use commit() to commit changes.
+  Use abort() to discard changes since the last commit.
+  Exit with ctrl+D does an implicit commit() but exit() does not.
+  The variable 'm' is the sample-list@lists.example.org mailing list
+  >>> from mailman.interfaces.action import Action
+  >>> for member in m.members.members:
+  ...     if not member.moderation_action:
+  ...         member.moderation_action = Action.defer
+  ...
+  >>> commit()
+  >>> exit()
+
+Note that we avoid altering ``moderation_action`` if it's already set,
+since previously identified spammers may have theirs set to something
+like ``Action.discard`` and we don't wish to reenable them. In this case
+``Action.defer`` is the explicit default processing path, which means
+continue to check the message against other rules like max recipients,
+message length, administrivia filtering, and so forth. While there is an
+``Action.accept`` it should be avoided, since it directly bypasses these
+valuable default processing rules.
+
+Once this action has been performed, switch the list's *Default action
+to take when a member posts to the list* from *Default processing* to
+*Hold for moderation* in Postorius. Any existing subscribers will have
+the same experience as before, but anyone who subscribes to the list
+from this point forward will have their posts held for moderation until
+a moderator changes the *Moderation* value to *Default processing* under
+the *Administration options* at the end of their subscriber page in
+Postorius.
+
 Django Admin Interface
 ======================