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Automatically stop data breaches and security threats caused by employees on email. Powered by machine learning, Tessian detects anomalies in real-time, integrating seamlessly with your email environment within minutes and starting protection in a day. Provides you with unparalleled visibility into human security risks to remediate threats and ensure compliance.

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Prevent Advanced Attacks on Email With Defender.

Inbound Email Security

Tessian Defender is a comprehensive inbound email security solution that automatically prevents a wide range of attacks that bypass Secure Email Gateways, while providing in-the-moment training to drive employees toward secure email behavior.

Built as a cloud native solution, Tessian Defender can be instantly deployed via API in MS365 environments, or seamlessly integrated with MS365, GSuite and MSExchange via connectors within minutes. Tessian learns within hours and starts protecting in a day.



Prevent Advanced Attacks on Email With Defender.

  • Advanced Threat Prevention and Enhanced Protection for MS365 and GSuite

    Defender protects against both known and unknown email attacks, including Business Email Compromise (BEC), Account Takeover (ATO), spear phishing, and all impersonation attacks that bypass Secure Email Gateways, Microsoft 365, and G Suite.


  • Easy Deployment

    Tessian Defender offers flexible deployment options that protects whether the email platform is in the cloud, on-premise, or hybrid. Tessian Defender can be instantly deployed using API for MS365 for advanced phishing protection or seamlessly integrated into MS365, G Suite and MS Exchange environments using connectors within minutes. Tessian learns within hours of deployment and automatically starts protection within 24 hours of deployment. No rules, policy configurations or MX Record changes needed.

  • Education and Awareness

    With Defender’s in-the-moment training, organizations can educate and empower users to build continuous email security awareness.


  • Reduce Admin Overhead

    Defender removes the burden on the SOC and admins by automating repetitive tasks such as maintaining triage and review. This eliminates the need for human verification of email threats, reducing FTE requirements.


Download The Datasheet

Prevent Inbound Email Attacks that Bypass Legacy Email Security Solutions.
See how you can turn your email data into your biggest defense against inbound email security threats with Tessian Defender.

How Defender Works

Prevent Inbound Attacks

Detect all indicators of inbound email attacks.


Defender’s behavioral intelligence leverages at least 12 months of historical data that includes the company’s emails, company network, as well as Tessian’s Global Threat Network, to detect all indicators of inbound email attacks. By using these broad range of signals from relationship graphs, deep inspection of the email content, and previous user behavior, Tessian can identify all inbound email attacks including:


Machine Learning Threat Prevention

Identify inbound email threats in real-time.


Tessian’s Human Layer Security (HLS) Engine analyzes all inbound emails in real-time and uses machine intelligence to automatically predict whether an incoming  email is malicious. Using a broad range of signals from relationship graphs, Tessian performs deep inspection of the email content, and previous user behavior.


Legacy approaches will scan for known malicious payloads such as links and attachments. This leaves these defenses vulnerable to zero-day threats, or attacks without payloads. Tessian will inspect the context of the email to determine indicators of an attack, notify the user, therefore not giving an opportunity of malware slipping through or the user to click.


Tessian + Microsoft

Enhance Microsoft Office 365 Email Security built-in Capabilities for Comprehensive Protection


Enhance Microsoft 365 threat-intel based Tessians next-gen, behavioral-based Integrated Email Security (ICES) approach effectively prevents all forms of advanced social engineering attacks by dynamically analyzing emails in real-time. Using behavioral intelligence from historical communications and conducting deep continent inspection that is needed to stop today advanced attacks
Integrates with Microsoft Office 365 via API provides a faster and easier deployment in seconds and protection within hours.


  • Faster and easier deployment of Tessian Defender now deploys in seconds, protects in hours and extends protection across any device. Automatically starts protecting without requiring email rerouting or changes to MX records.
  • Improved protection for end-users while offering in-the-moment training. Tessian’s soft quarantine, or user quarantine, approach uniquely protects organizations from being compromised by an end user accidentally opening a malicious attachment or clicking a URL before they’ve had an opportunity to determine the email safe.
  • Low management overhead that deploys in seconds with no ongoing management aside from adding new users to Directory Groups. No need to upgrade as you are always on the latest version. Admin quarantine automatically quarantines known malicious emails enabling SOC teams to quickly act on risky phishing attacks.
In-The-Moment Training

In-the-Moment Training to Stop Email Attacks Where They Start


When unsafe emails are detected, employees can either receive in-the-moment alerts with clear, simple explanations of potential risks or emails can be directly quarantined for inspection and approval by Security Analysts.


  • Non-disruptive in-the-moment training and awareness is provided to employees through contextualized, easy to understand warning messages.
  • Risk trends downward as users learn more about security through in-the-moment warnings, becoming better at spotting attacks and lowering click-through rates on identified threats.
Tessian Human Layer Intelligence

Granular Visibility to Quickly Prevent, Mitigate and Remediate Inbound Email Attacks


Built within the Tessian HLS Platform, HLS Intelligence allows security teams to seamlessly access insights, intelligence, and tools that significantly reduce manual incident investigation time and allow for rapid response to impersonation threats.  With Tessian HLS Intelligence, security teams can:


  • Readily view top threats, top target users, and detailed breakdown of anomalous events detected by Tessian Defender
  • Remediate with speed. Quarantine, clawback unsafe emails from users’ inboxes, or update blacklists to prevent similar threats with a single click
  • Future proof defenses using shared threat intelligence and automatically block blacklisted domains across the Tessian ecosystem. No rules needed
  • Quantify risks, compare trends, and influence employees to adopt a secure behaviorBenchmark impersonation risk levels against industry peers


Tessian Defender secures all enterprise email environments.
Tessian is committed to helping our customers protect their people and meet their compliance needs. Through Tessian HLS Intelligence, you can directly integrate with your SIEM/SOAR via a RESTful HTTP API.
View Tessian's integrations, compatibility and partnerships →

Download the Latest Defender Resources

  • Defender Product Datasheet

    Tessian Defender is a comprehensive inbound email security solution that automatically prevents a wide range of attacks that bypass Secure Email Gateways, while providing in-the-moment training to drive employees toward secure email behavior.


  • Stop External Account Takeover with Defender

    Email security is no longer limited to securing an organization’s own email platform. There is a growing trend where attackers gain access to the email account of a trusted sender, impersonate the sender and use it to conduct fraudulent activities.


  • Tessian Defender Threat Catalogue

    Learn how Tessian Defender detects and prevents inbound emails attacks that slip right past native email tools and legacy solutions.




Prevent Inbound Email Attacks

See Tessian Defender in Action.
Book a demo and see first hand how Tessian Defender detects inbound email attacks that bypass legacy email security solutions.