As the number and size of mailing lists at your site become large, you might wish to install a software package that automates list management. We show four of the more mature packages here. Many other packages exist (some good, many immature), and you can find them by searching the Web.
The Majordomo mailing-list management software was originally written by Brent Chapman using the perl(1) language. Its chief features are that it allows users to subscribe to and remove themselves from lists without list manager intervention and that it allows list managers to manage lists remotely. In addition, users can obtain help and list descriptions with simple mail requests. Note that Majordomo aids in managing a list (the list addresses) but does not aid in list moderation (the contents of mail messages). But Majordomo does catch administrative mail erroneously sent to the list as whole. Majordomo is available via anonymous FTP from ftp://FTP.GreatCircle.COM/pub/majordomo/.
The Mailman mailing-list management software was written and is distributed as part of the GNU project. It claims to be fully web-based for ease of management. Even list managers can manage lists entirely over the Web. Mailman is written in Python (with some C code for security). The Mailman package is available from http://www.gnu.org/software/mailman/mailman.html.
The ListProcessor system was written by Tasos Kotsikonas. It is an automated system for managing mailing lists that replaces the aliases file for that use. According to the author, it includes support for "public and private hierarchical archives, moderated lists, peer lists, peer servers, private lists, address aliasing, news connections and gateways, mail queueing, list ownership, owner preferences, crash recovery, and batch processing." The system also accepts Internet connections for "live" processing of requests at port 372 (as assigned by the IANA). The ListProcessor system is available via anonymous ftp from http://www.listserv.net/.
 IANA stands for Internet Assigned Numbers Authority.
According to its author, Murray S. Kucherawy, the ListManager system "is written entirely in C, so it's faster and more efficient than mailing list systems based on scripted languages. Rather than flat files, it uses fast B-tree databases courtesy of Sleepycat Software for faster performance." This is the mailing-list software used by sendmail.org. Among the features claimed on its web site are:
Automatic mail-alias table updates
Moderated, private, invite-only, and "hidden" lists
List archiving, with access controls and lifetime limits
Subscription confirmation, new subscriber probation, and subscriber renewals
Address validation check levels: none, syntax only, MX, and SMTP
HTTP interface and extensive help
Password security on subscriptions and list modifications
Arbitrary file storage, and Unix mailbox-format archives
MIME attachment filtering and loop detection
Automatic subscriber addition features
Quotation limiting, access control lists, digest sorting, and list inclusions
Subscriber domain matching
Rotating footers, and separate headers and footers for digests
Crontab-like digest distribution settings
Distribution of digests by size, time, or number of submissions
Welcome and farewell messages
Powerful command-line features such as "foreach" and scripting
The Listmanager software is available at http://www.listmanager.org/.