Email systems
nRed Hat Enterprise Linux
nMail transport agent is Postfix
nCyrus IMAP is
the mailstore
nPHP, Perl and PostgreSQL for scripting
and database
nHorde IMP webmail
nSpamAssassin
for spam identification (along with public RBLs and filter rules)
nSpamity to manage the spam quarantine
function
nSympa for
listserver support
nCLAM Anti-Virus
nAMaViSd-new to glue the services
together