NeutronMail
Description: NeutronMail is an open-source, privacy-focused email service. It uses end-to-end encryption to secure messages, and has security measures in place to prevent data harvesting, tracking, and ads.
Type: software
Pricing: Open Source
Zimbra Collaboration Suite
Description: Zimbra Collaboration Suite is an open source email and collaboration platform. It includes email, contacts, calendar, document management, and other collaboration tools. Zimbra is designed for enterprises and service providers.
Type: software
Pricing: Open Source