Scrollout F1 is an easy-to-use anti-spam email gateway designed for Linux and Windows email system administrators.
Scrollout F1 aims to be a simple, yet powerful and already configured email firewall with free anti-spam and anti-virus protection so you can secure any email servers you maintain. It supports most popular email servers including Microsoft Exchange, Lotus Domino, Postfix, Exim, Sendmail, and Qmail.
It has Built-in multi-layer security levels that are easy to configure and combines simplicity with effective protection using an additional set of rules & filters. It is available as 32-bit and 64-bit in an ISO image.
For 5,000 messages a day you only need 30 GB of drive space and 1 GB of RAM. No requirements for the processor is mentioned so assume it will run on older hardware.
Scrollout F1 has too many features (whitelist, blacklist, fingerprint, newsletter rules, quarantines, scoring) to continue here but we think you'll be impressed.