vpopmail provides an easy way to manage virtual domains and virtual
accounts on a qmail mail server.

Features:

. Automates all qmail file modifications into documented command line
  programs

. Support for named and IP-based virtual domains

. NFS safe

. dynamic directory creation for scalability using fill-in balanced 3
  level tree

. understands standard qmail .qmail directives

. interacts well with qmailadmin for web-based administration, courier-imap
  for IMAP support, and sqwebmail for web-based mail.

WWW: http://inter7.com/vpopmail/