Used mostly for discussion between developers of new features and testers of pre-release versions. See addresses in the FAQ. Send mail to email@example.com with the single word
help in the body of the message , and you will get mail explaining how to subscribe to the many Linux mailing lists there. Save this mail, as it tells you how to unsubscribe from the lists, and if you post annoying messages to the list complaining about not being able to get off the list (because you didn't follow instructions and save the mail telling you how to unsubscribe), you will likely be flamed for wasting international bandwidth and money.