"ISPMan is a distributed system to manage components of ISP from a central management interface. These components run accross frontend and backend servers. Front end servers are the machines that are directly visible to your internet users. For example your web (eg. Apache), SMTP (eg. Postfix), DNS (eg. Bind) servers while backend servers can be Mailbox servers (eg. Cyrus IMAP server), Fileservers, database servers etc."

See also LinuxLDAP, SMTP, Linux, or Apache