This is additional information for list owners. If you require additional assistance email mailman at lists.gno.org.
Read the documentation! You may want to peruse this page for an overview of possibilities first, but read the documentation!
List Users' documentation (that's for the people subscribed to your list).
The GNU Mailman home page.
Should your list be public or private? The answer depends a lot on the subject material and how the list being used. Here are some comparisons:
The only real difference between a public and a private list is whether or not the list name appears on this site's list information page. Who can post to the list, whether there are list archives, and whether or not the general public can see the list archives are all controlled independently.
If you want people to self register via email based on information provided by a web page (the most common mode of operations), then it pretty much has to be a public list. If you make it a private list and elsewhere create a web page that has a link to the list's information page, it is effectively a public list.
If your list has a restricted and fairly static membership, where individuals are emailed the list information page (or added by the list owner), then having a private list can reduce the amount of work required of the moderators and list owner.
If the list is public, then it exposes the list address to spam harvesters. This is mitigated by the type of antispam measures you take when configuring your list.
If you are migrating from an existing mailing list, it is possible to import your existing list (read the Official Documentation for details).
However, before you do so, please let your existing list members know what you are doing so that they don't start getting mail from lists.gno.org out of the blue and report the server to various antispam databases. This just pisses people off, including both your subscribers and me.
Your mailing list can potentially expose information and email addresses. Consider your responsibilities to your members and set things up appropriately:
Should it be a public or private list?
You can control whether or not list members are allowed to see who else is on the list. Except in special circumstances, you should probably turn this off.
Should your messages be archived?
If you have a message archive, should it be restricted to members-only?
If you have a message archive, should email addresses in it be obfuscated to make it (slightly) harder for spammers to harvest them? (This is more of a factor for archives that are publicly available.)
This server uses various anti-spam measures that will normally block problems during the SMTP conversation. The nature of the beast, however, is that if your list address gets harvested (and it will, at least for public lists), then you as moderator or list owner will end up having to reject at least some inbound spam. How bad it gets and how much work is required by the moderators can be controlled by the list owner by the appropriate configuration decisions.
(Note that the only mail that is ever rejected by the server without the sender being notified is that which is positively identified as containing a computer virus. It is possible to configure individual mailing lists to reject or drop messages, but no such operations happen at the system level outside the control of the list owner.)
The effectiveness of some of the following options can be dependent on whether or not they are implemented at the time of list creation, or only after the address has been harvested by spammers.
You may operate a fully moderated list. Nothing gets sent to the membership until a human approves it.
You may configure your list so that posts by members (and possibly other specific addresses) get through, but everything else gets automatically deleted or rejected. This makes it easier to moderate, however (especially in the deleted case) legitimate senders may not realize that their mail isn't getting through. This can happen, for example, if someone is subscribed as email@example.com but sends from a second address, firstname.lastname@example.org. See also the FAQ regarding aliases.
If you configure your list in this fashion, please ensure your reject message contains a reference to the FAQ page.
You may configure your list so that newly subscribed members are automatically moderated. If the member is seen to be posting on-topic material, you can clear the moderation flag for that member. This is a good option for lists that allow anyone to subscribe to them, as it helps avoid the problem of a spammer subscribing, spamming everyone on the list, then moving on.
You may wish to add a rule to check the spam score of incoming messages, and either reject or hold for moderation any messages that appear to be spam. See the FAQ for details.
You may configure your list so that subscription requests have to be authorized. This is probably only suitable if you know, or can otherwise identify legitimate subscription requests. Otherwise, it's just extra work for the moderators.
You can reenable moderation for individual members if they cause a problem.
You can unsubscribe (and ban) individual members if they cause a problem.
You can automatically reject or discard mail from specific addresses.
You can use the emergency moderation settings, in which case all postings will be moderated. Use this if an unmoderated list is getting out of control due to a flame war or similar problem.
By default, every list member will receive a monthly reminder of the lists to which they belong, how to reach the user's web interface, and what their password is. If they belong to more than one list on this server, they will get a single notification for all lists.
This Is A Good Thing.
It allows the users to more easily maintain their subscriptions and gives a sense of empowerment. It also reduces headaches of the "I don't want to be on your list anymore, get me off!" variety. If individual users don't like the reminders, they can disable them.
While it is possible to disable the reminders for an entire list, I would appreciate it if you did not do so. If you really want to make the mailing list totally transparent to them, stop using it and set up an alias on your personal mail client.