Question: I want to configure a mailing list to be used as one-way announcement/news list.

Answer: There is no specific Mailman setting for this, but the default configuration values as created through the normal Savannah mailing list interface should suffice. The principle is simply to avoid approving messages that you don't want to go through.

Specifically, under privacy:

• moderate new members
• hold messages from moderated members
• hold messages from non-members

Subscribe yourself, and then unmoderate yourself in "members management".

ListHelperAntiSpam has more about mailing list configuration. We do not recommend ever using anything but "hold" (not accept, not discard, not reject), for reasons explained there.