A good site will make it easy for you to set up your list, and manage it over time. An alternative is to find a university system generous enough to house such services for other professionals. One such example is St. John's University in New York.
Some online services are also available for free.
They will prove invaluable over time. Join a listserv discussion group online, so as to have access to other listserv owners who run into management problems. Use your search engine or look for newsgroups devoted to this topic. Clearly outline your behavioral expectations for subscribers. While it may seem overly paternalistic to cover all forms of negative behavior when welcoming new members, the realities of anonymous online discussion have led to remarkably negative displays of human behavior, even among professionals.