Alternatives to: Mimecast

AgentJ is a free, Open Source anti-spam solution with a web interface, human authentication, and integration with various identity and security providers.

CleanMail is a cloud-based email security relay that uses AI-powered filtering to protect against spam, viruses, and phishing attacks.

Proxmox Mail Gateway is an Open Source email security platform that protects mail servers from various threats through a centralized, web-based interface.

Rspamd is a high-performance, Open Source spam filtering system with a Lua API for custom rules and plugin development.

Rspamd is a high-performance, Open Source spam filtering system with a powerful Lua API for customization.