Proxmox Mail Gateway

Proxmox Mail Gateway is the leading open-source email security solution helping you to protect your mail server against all email threats from the moment they emerge. The flexible architecture combined with the userfriendly, web-based management interface, allows IT professionals and businesses to control all incoming and outgoing emails with ease, and to protect their users from spam, viruses, phishing and trojans.

Organizations of any size can easily deploy and implement the anti-spam and anti-virus platform in just a few minutes. The full featured mail proxy is deployed between the firewall and the internal mail server, and allows to control all email traffic from a single platform. Proxmox helps you to easily maintain a secure and professional email communication, ensure business continuity, and gain high business reputation as well as customer satisfaction.

You can read about this and other PROXMOX products here