2.7 The Privacy Options Category

The Privacy category lets you control how much of the list's information is public, as well as who can send messages to your list. It also contains some spam detection filters. Note that this section is not used to control whether your list's archives are public or private; for that, use the category.

There are four sub-categories:

Subscription rules - i.e. the rules for joining and leaving your mailing list
Sender filters - the rules for who may post messages to your list
Recipient filters - moderation rules based on the recipient of the message
Spam filters - some regular expression based rules for header matching

The sender, recipient, and spam filtering rules are part of the general list moderation features of Mailman. When a message is posted to the list, it is matched against a number of criteria, the outcome of which determines whether the message is reflected to the membership or not. In general, the outcome is one of four states:

Approved or Accepted - the message may be sent on to the members of the mailing list.
Hold - the message will be held for moderator approval. The list owners and moderators will then have to explicitly approve the message before the list members will see it.
Reject - the message is bounced back to the original sender, often with a notice containing the reason the message was rejected. The list members never see rejected messages.
Discard - the message is simply thrown away without further processing.

Many of the fields in this section are text boxes accepting addresses, one per line. Unless otherwise noted, these also accept regular expressions which will be matched against an address, if the line begins with a ^ (caret) character.