[CentOS] looking for alternative to SME & Clark Connect

> I'm looking for a (preferably free) alternative to SME / Clark Connect.

> I basically need the following:
> 
> - firewall
> - nat
> - VPN
> - bandwidth limiting / monitoring
> - email (SMTP / POP3 / IMAP) & groupware
> - file & printer sharing
> - RAID support
> - if possible fail-over / high availability support.

Here is a free mail server solution for RHEL/CentOS 5.x: 
http://code.google.com/p/iredmail/

-- 
Best regards.

Zhang Huangbin

- Open Source Mail Server Solution for RHEL/CentOS 5.x:
  http://code.google.com/p/iredmail/