L-Soft (http://www.lsoft.com/) is a software company focusing on listserv and email server software. It was founded in 1994 by Eric Thomas in order to control the of his listserv software when he couldn't come to terms with CREN (Corporation for Research and Educational Networking) and EARN (European Academic and Research Network) for funding of his project, Revised Listserver, which he originally wrote in 1986. When L-Soft started, LISTSERV was its main offering.
Today, their products include:
All of their software runs on Windows, and they have versions for UNIX-based systems too. On their website they offer free downloads of trial versions of LISTSERV and LSMTP, and also documentation for their software (which is quite complete and informative).
Their customers include:
L-Soft also offers training and consulting for their software.
The latest version of their LISTSERV software (their flagship product) is 1.8e, which includes virus scanning, and a re-designed web admin (for administrating listserves), among other new features.