You can find a lot of information here. Here you can post wills, biographies, deeds, pensions, bibles, obituaries and place queries. A mailing list is like a discussion group, people helping people about a specific topic. The name of the mailing list tells you what the topic is.
Instructions are further down the page.
Here you can search through back issues of various mailing lists. This will get you a copy of every single message posted to the Oxford County list. This will get you a copy of every single message posted to the Cumberland County list. This will get you a copy of every single message posted to the Maine list.