Mailing lists may also be moderated, in which case the owner can censor messages sent to the list. The ListServer is a system that automates mailing lists and archives. The system also maintains archives of files that users may retrieve. All users interact with the ListServer by e-mail. Each list has one owner and any number of moderators .
Moderators assist the owner with management tasks, such as helping users having trouble subscribing.
The owner, who has all the privileges of the moderators, is sent e-mail by the ListServer in the case of errors, unauthorised access to list functions, etc. With private lists, it is the owner who approves or rejects subscription requests. In addition, the e-mail address of the owner is verified for such requests. Each mailing list may have its messages automatically archived. The system may also keep archives of patches, and other types of files.