A list server is a computer that collects and distributes electronic mail messages.
Any message sent to the listserver is distributed to a list of subscribers.
It allows groups of people, who have subscribed to the list, to communicate easily on the internet. The discussions can be moderated or unmoderated. Most are unmoderated. On a moderated list all messages are screened prior to being posted. On an unmoderated list, the messages show up without any screening.