Configure Mailman as an announce-only Newsletter list
4) In the same page (General Options), select “No” to the question “Send monthly password reminders?”
5) “Send mail to poster when their posting is held for approval?” – Check the “No” option.
6) Still in General Options, to the question “Should postings include the List-Post: header?“, select “No”.
7) After General Options, the next section we need to care about in this guide, is the Membership section. Go there, and at its first page “Membership List / Additional Member Tasks” check the “On” option at “Set everyone’s moderation bit, including those members not currently visible.” This means that not a single post will be distributed un-moderated. You want to moderate even your own posts, in case someone impersonates you, using the same address as yours.
8) Leaving the Membership section, go next to Non-digest options. Select “Yes” to the question “Can subscribers choose to receive mail immediately, rather than in batched digests?“, since you are not going to have digests at all.
9) Next, to the section of Digest options, select “No” to the question “Can list members choose to receive list traffic bunched in digests?“, and select “Regular” to the question “Which delivery mode is the default for new users?”