SecurityGateway, from MDaemon

Security Gateway for Email Servers, from MDaemon offers Protection from External Email Threats, Protection from Internal Email Threats, Administrator Options, Performance Features, and Detailed Logs and Comprehensive Reports. Security Gateway helps analyze, manage, and report on the inbound and outbound email traffic patterns of Microsoft Exchange Server or any other SMTP email server. It is available as an on-premise solution, and there is a also a hosted version.

SecurityGateway, from MDaemon starts at $25.