The Cyrus IMAP server is generally intended to be run on sealed systems, where normal users are not permitted to log in. The mailbox database is stored in parts of the filesystem that are private to Cyrus. All user access to mail is through the IMAP, POP3, or KPOP protocols. The private mailbox database design gives the server large advantages in efficiency, scalability, and administratability. Multiple concurrent read/write connections to the same mailbox are permitted. The server supports access control lists on mailboxes and storage quotas on mailbox hierarchies, multiple SASL mechanisms, and the Sieve mail filtering language.
DarkFire IRCd is an efficient, modern, and flexible IRC server used primarily on the DarkFire IRC Network. Originally based on Dreamforge, it has numerous enhancements and a wider variety of features. It features an efficient server to server protocol, a wide variety of user and operator commands, and a flexible protocol.