Listserv is software for managing mailing lists: creating lists, distributing emails over the list, adding new subscribers, and adjusting settings. It can be operated via a Web interface, by sending email commands, or via TCP. liblistserv is the glue between listserv and your C program for manipulating or querying a mailing list. By calling the provided functions, your program does not need to parse the results. Liblistserv is a reentrant library, written in C, meant for communication over TCP with a running Listserv instance.
