Debian/Linux MX server
I needed to install some incoming mail servers (MX servers) to filter emails before delivering them to customers servers. So the need is to accept mails for a fixed list of domains, check for viruses and spams, then route them to customers servers for delivery. The distribution is Debian 6, the mailserver is Exim. The antivirus check is done by ClamAV and the antispam with Spamassassin + Pyzor + Razor + DCC + DNSBL....