11.2 What does Mailman do to help protect me from unsolicited bulk email (spam)?

A technical list's archives may include answers to a range of different questions. Often, the people who have posted these answers would be happy to help someone who doesn't quite understand the answer, and don't mind giving their address out for that purpose. But although it would be wonderful if everyone could contact each other easily, we also want to make sure that the list and list archives are not abused by people who send spam.

To make a range of options available to list administrators, Mailman allows a variety of configurations to help protect email addresses. Many of these settings are optional to the list administrator, so your particular list may be set up in many ways. List administrators must walk a fine line between protecting subscribers and making it difficult for people to get in touch.

Subscriber lists
- The list administrator can choose to have the subscriber list public, viewable only to list members, or viewable only to list administrators.
- The subscriber list is shown with the addresses obscured to make it difficult for spam harvesters to collect your address.
- You can choose to have your address hidden from the subscriber list. (See Section 10.4 for more information.)
- Note: The entire subscriber list is always available to the list administrators.
List archives
- The list administrator can choose for the archives to be public, viewable only to members (private), or completely unavailable.
- The HTML archives which are created by Pipermail (the archiving program which comes default with Mailman) contain only obscured addresses. Other archiving programs are available and can do different levels of obfuscation to make addresses less readable.
- If you wish to be more sure, you can set the mail header X-no-archive: and Mailman will not archive your posts. Warning: This does not stop other members from quoting your posts, possibly even including your email address.
Limited posting to the lists
- The list administrator can choose who can post to the list. Most lists are either moderated (a moderator or administrator reviews each posting), set so only subscribers may post to the list, or allow anyone to post to the list.
- By allowing only subscribers to post to a list, Mailman often blocks all spam and some viruses from being sent through the list. As such, this is a fairly common setting used by list administrators.
Anonymous lists
- Lists can also be made fully anonymous: all identifying information about the sender is stripped from the header before the message is sent on.
- This is not typically used for anti-spam measures (it has other uses), but it could be used in that way if desired.

Of course, many address-obscuring methods can be circumvented by determined people, so be aware that the protections used may not be enough.