By default, all the public pages come in the standard Mailman livery, but if you want to change this (for example to use your own house style), you need to go to /usr/local/mailman/templates/en/ and copy the files there. You need a Developer or Business Email account to do this.
Make duplicates in your /home/yourusername/mailman/list.yourdomain.yourtld/templates/en/
directory, for example:
In this directory, you can change the style sheet, contents etc. as required. Any files placed in this directory will be used by Mailman, instead of the generic ones as modified by any editing described above. Take care not to rename them or disable any required form functionality in the pages.
Editing post headers and footers etc.
The headers and footers added to posts before they are sent out to members are specified in the Non-digest and Digest options pages, respectively. Use the link provided on the pages to get details of the parameters you can include.
Some other snippets can be edited in the General Options page:
The introductory description at the top of the list information page.
The prefix that appears in the subject line of email posts sent out to the members. By default, the list name in square brackets.
Text to be added after Welcome to the yourlistname mailing list in the welcome message to new subscribers.
An optional goodbye message for people leaving the list.
Announcement-only lists should normally be low-volume, so you can use this configuration for most of them:
If there are already ordinary members, at the bottom of the Membership Management page, select Set everyone's moderation bit (but see below for more on posting policy).
In Non-digest options, select Can subscribers choose to receive mail immediately
In Digest options, deselect Can subscribers choose digests?
In Privacy Options, you normally want to choose:
Confirm for What steps are required for subscription?
List admin for Who can view subscription list
Yes for Should new list member postings be moderated?
Reject for Action to take when a moderated member posts and add a message like "This is an announcement list. You cannot post any messages to" in Text to include.
Reject for Action to take for postings
No for Action to take for postings from non-members
In Auto-Responder, choose 0 for Number of days between auto-responses
The end result is a list to which no-one will be able to post without moderator intervention, and everyone will get an immediate message advising that their post is held when they try to post. You have two choices here for posting announcements:
You can de-select the mod flags of the users who can make announcements, but this is not very secure because email addresses can easily be guessed and forged.
You can confirm the announcements individually (see the section "Moderating a mailing list").