The cactuscode.org website (http://cactuscode.org/community/mailinglists/) says:
Cactus maintainer mailing list: firstname.lastname@example.org [archives] This list is not public. You can send questions, comments, or complaints to this list which you do not want to make in public.
However, when I send an email to this list, I receive a response saying that my message is awaiting moderation. If the list is intended for users to send email to, and the readership of the list is small, there is no need for moderation, and the automated reply is confusing.