Mailman
Description: Mailman is an open source mailing list management system. It helps manage email discussion and announcement lists, allowing users to subscribe and unsubscribe, and helping admins moderate and post to the lists.
Type: software
Pricing: Free
Nmap
Description: Nmap is an open source network discovery and security auditing tool. It is used to discover hosts and services on a network and to detect potential vulnerabilities.
Type: software
Pricing: Free