Our Digests, the most popular format allows custom headers and footers. Each night the list members will receive a single email message containing all the contributed messages to that list in that day.
And as the list administrator (you can be the only one or one of several) you can choose to moderate the list or leave it open, unmoderated.
Saving archives? Archives are stored as a searchable forum, by date, subject or author, both in plain text and HTML. This is especially helpful for research and discussion history.