# GreatHorn

GreatHorn is a cybersecurity company based in the United States, founded in 2015. It has 2 products listed on CybersecTools.

> Cloud-native email security for Office 365 and G Suite environments

Source: https://cybersectools.com/companies/greathorn · Updated January 2026

## Quick facts

- Category: [Email & Messaging Security](https://cybersectools.com/categories/email-security)
- Type: Product vendor
- Headquarters: United States
- Founded: 2015
- Products listed: 2
- Website: [greathorn.com](https://www.greathorn.com/)

## What does GreatHorn do?

GreatHorn provides cloud-native email security solutions designed specifically for organizations using Office 365 and G Suite (Google Workspace). The company's platform protects against targeted phishing attacks, business email compromise (BEC), malware, and ransomware through a combination of machine learning, automation, and behavioral analysis.

The platform operates without requiring mail routing or network-level changes, using OAuth-based access provisioning to integrate with cloud email systems. GreatHorn analyzes email content in memory within containerized cloud environments, evaluating hundreds of risk factors including relationships, communication patterns, and technical fingerprints. The system automatically adapts to each organization's unique environment and communication behaviors.

GreatHorn's approach encompasses protection at three stages: before attacks reach users (perimeter), during user engagement (point of interaction), and after incidents occur (remediation). The platform includes threat detection capabilities, user engagement tools, and integrated email remediation features. The company emphasizes empowering employees to identify threats by providing contextual information alongside automated protection.

The company was founded by cybersecurity veterans with backgrounds at organizations including @stake, CloudLock, Conjur, and Courion. GreatHorn maintains SOC 2 Type 2 certification and Cloud Security Alliance STAR certification. The platform's threat intelligence is built from analysis of hundreds of millions of email threats, with all end-user data anonymized and client-identifiable metadata stored in single-tenant databases.

Categories: [Email & Messaging Security](https://cybersectools.com/categories/email-security), [Cloud Security](https://cybersectools.com/categories/cloud-security), [Threat Intelligence](https://cybersectools.com/categories/threat-intelligence), [AI Security](https://cybersectools.com/categories/ai-security)

## GreatHorn products

- [GreatHorn Email Security](https://cybersectools.com/tools/greathorn-email-security): Cloud-native email security platform for phishing detection and response (commercial)
- [GreatHorn Mailbox Intelligence](https://cybersectools.com/tools/greathorn-mailbox-intelligence): Email security tool empowering users to identify & report phishing threats (commercial)

---

More on GreatHorn: funding, momentum, hiring and news, plus the full product and company record, are available through the Mandos MCP Server (paid plans), which connects to AI assistants: https://mandos.io/mcp?utm_source=cybersectools.com&utm_medium=company-md