1. Log into the list admin interface: http://yourlistdomain/mailman/admin/listname_yourlistdomain
2. General Options:
- "Should administrator get notices of subscribes and unsubscribes?" Yes.
3. Privacy Options --> Subscription Rules
- "Advertise this list when people ask what lists are on this machine?" No.
- "What steps are required for subscription?" Confirm and Approve
- "Who can view subscription list?" List members (the default) for community lists
- "Who can view subscription list?" List admin only for announcement lists
4. Privacy Options --> Sender Filters
- "By default, should new list member postings be moderated?" Yes.
- "Action to take for postings from non-members for which no explicit action is defined." Discard.
- "Should messages from non-members, which are automatically discarded, be forwarded to the list moderator?" No.
5. Privacy Options --> Recipient Filters
- "Ceiling on acceptable number of recipients for a posting." 4
6. Archiving Options
- "Is archive file source for public or private archival?" Private
The above settings should make your list very secure and should meet the security policies of most organizations. As always if you have any questions feel free to submit a support ticket via your client area.