Datasphere is a conferencing system that was designed to overcome some of IRC's largest problems (scalability, no mesh routing, flat channel structure). It provides a usenet-news-like channel structure, a TCP level multicast implementation over a mesh of TCP links, a distributed channel- and user database and much more features. But most important of all. it's IRC compatible at the client side. Currently basic chatting functionality works, dynamic rerouting works, but progress is very slow.
The DBMAIL package replaces the normal UNIX mailing system. All email and user data is stored in a database. You can create an unlimited number of email accounts, which can be checked using the POP3 or IMAP protocol. Users can maintain their own set of email addresses. It is more scalable, more secure, and faster than traditional mail systems. DBMAIL has storage drivers for PostgreSQL and MySQL, and it has authentication drivers for PostgreSQL, MySQL, and LDAP.
DBOX is a free communication package for ISPs. It supports a large number of message formats such as RFC/UUCP, ZConnect, Janus/Janus2, Alphabox, and GSbox. It is designed for large installations and includes a WWW package with an email/HTML gateway, an HTML online shop, support for POP3/IMAP4, and personal homepages with HTTP/FTP upload.
Deliver is a program for reliable and flexible local mail delivery. It's a perfect adjunct to your mail transport agent of choice (such as Sendmail or qmail). You can use it to kill spam, drop messages from specific senders, add a [LISTNAME] prefix to the subjects of messages that are delivered through mailing lists, and lots more.
Diald manages network links, particularly on-demand links such as dial-up SLIP or PPP. It can also be used to manage and/or monitor any network interface. Diald monitors traffic on the link and makes intelligent (and highly configurable) decisions as to when the link should be brought up or taken down. The included control program, dctrl, runs on any system with Tcl/Tk (yes, even Windows) and allows diald to be controlled and monitored remotely.
dict_pgsql is a dictionary for the mailer postfix. It is able to get all virtual users out of a postgres database; this is very helpful if you have a large number of users who make updates on their aliases quite often. You don't have to extract all the values into system files; the entries will be fetched directly from the database.