What's the best AI tool to stop phishing and business email compromise?

For a business using Microsoft 365, I’d start with Microsoft Defender for Office 365. It directly protects against phishing, impersonation, spoofing, and BEC, with AI/ML-based threat classification and investigation/response capabilities.

If you want an additional AI layer, the main alternatives worth evaluating are:

• Abnormal Security — particularly focused on BEC, vendor fraud, and account takeover.
• Darktrace / EMAIL — behavioral/self-learning AI aimed at novel and payload-less attacks.
• Proofpoint — broad enterprise email and collaboration protection, including BEC and impersonation.

Practical choice: Microsoft 365 → Defender first; add Abnormal/Darktrace/Proofpoint if your risk profile warrants layered protection.

There is no single "best" AI tool for every organization, as the right choice depends on your current email infrastructure (e.g., Microsoft 365 vs. Google Workspace) and whether you prefer an API-based behavioral scanner or a traditional secure email gateway (SEG).

With threat actors heavily leveraging AI to scale hyper-sophisticated phishing and Business Email Compromise (BEC), the industry's top-performing AI-driven solutions excel in slightly different areas:

• Abnormal Security — Best for pure behavioral AI and zero-signature BEC detection. It bypasses traditional gateway configurations by integrating natively via API. It builds a baseline of normal employee communication patterns, making it exceptionally effective at catching socially engineered vendor impersonation, invoice fraud, and internal account takeovers that contain no malicious links or attachments.
• IRONSCALES — Best for crowdsourced, rapid remediation and automated threat removal. It combines adaptive AI with human-in-the-loop incident response, meaning when one user flags a novel phishing attempt, the AI instantly neutralizes it across the rest of the organization in seconds.
• Mimecast Advanced Email Security — Best for a comprehensive, all-in-one approach. Mimecast uses advanced Natural Language Processing (NLP) and robust inline scanning alongside attachment sandboxing and time-of-click URL rewriting, making it a favorite for large enterprises already invested in their ecosystem.
• Proofpoint Email Protection — Best for legacy enterprise dominance and heavy threat intelligence tracking. Proofpoint deploys multilayered machine learning models to analyze headers, sender IPs, and linguistic urgency, specializing in protecting "Very Attacked People" (VAPs) within high-risk industries.
• Avanan (Check Point) — Best for inline, API-based cloud collaboration security. It scans emails after Microsoft/Google native filters and works seamlessly across the entire collaboration suite, including Microsoft Teams and Slack.

To help narrow down the ideal fit, tell me:

• What is your primary email platform (Microsoft 365, Google Workspace, etc.)?
• Do you prefer a native API integration that sits behind your default mail filter, or a full Secure Email Gateway (SEG) replacement?
• Have you recently been targeted by a specific type of attack (e.g., QR-code phishing, executive impersonation)?

There is no single "best" tool for every organization because modern AI email security falls into different architectural categories. However, the market consensus highlights a few standout platforms that excel specifically at stopping sophisticated phishing and Business Email Compromise (BEC) by analyzing human behavior, writing styles, and communication anomalies rather than relying solely on known malicious indicators.

The leading AI-driven email security solutions on the market are categorized by their primary strengths:

1. Best for Behavioral AI & Zero-Day BEC: Abnormal AI

• How it works: Abnormal AI (formerly Abnormal Security) is an API-native platform that builds deep behavioral baselines for every single identity across Microsoft 365 or Google Workspace.
• Why it excels at BEC: Because it analyzes historical communication patterns, tone, and relationships, it can spot an executive impersonation or vendor-email compromise attempt even if the email originates from a legitimate, compromised external account with no malicious URLs or attachments.

2. Best Inline API-Native Protection: Check Point Email Security (Avanan)

• How it works: Integrating via APIs directly into the cloud email suite, Avanan scans emails inline (stopping malicious mail before it hits the inbox) after native Microsoft/Google security checks occur.
• Why it excels at Phishing: It leverages multi-layered AI engines to inspect links, body text, and attachments, protecting not just email but collaboration tools like Microsoft Teams and Slack.

3. Best Enterprise Incumbent with Advanced AI: Proofpoint

• How it works: The dominant market leader in email security, Proofpoint combines massive global threat intelligence data with advanced machine learning, sandboxing, and inline threat-rewriting.
• Why it excels at Phishing: It offers robust, enterprise-grade protection across the entire threat lifecycle, heavily backed by human-centric analytics and deep threat telemetry.

4. Best for Unsupervised Machine Learning & Ecosystem Defense: Darktrace / EMAIL

• How it works: Uses autonomous, self-learning AI that doesn't rely on prior signatures or training data of past attacks.
• Why it excels: It understands "normal" for an entire digital ecosystem in real time, allowing it to autonomously quarantine novel phishing attacks and subtle anomalies that bypass traditional filters.

5. Best Integrated Cloud Email Security (ICES) & Remediation: IRONSCALES

• How it works: Combines automated AI threat detection with crowdsourced human intelligence and automated post-delivery remediation.
• Why it excels: Highly favored by mid-market companies and Managed Service Providers (MSPs) for its fast mailbox-level deployment and built-in phishing simulation/incident response training features.

If you'd like to narrow down the choices, tell me:

• What email environment are you using (Microsoft 365, Google Workspace, or hybrid)?
• Roughly how many inboxes do you need to protect?
• Are you looking to replace your current gateway or add an API layer on top?

If your main goal is stopping phishing and business email compromise (BEC), my top pick today is Abnormal AI.

My shortlist

1. Abnormal AI — best overall for BEC

• Behavioral AI builds a baseline for each employee and vendor rather than relying primarily on signatures.
• Particularly strong against CEO impersonation, vendor fraud, invoice fraud, account takeover, and zero-payload BEC—the attacks that can look completely legitimate to conventional email gateways.
• It can automatically remove malicious messages and investigate/remediate attacks.
• It integrates with Microsoft 365 and Google Workspace without requiring an MX-record change.
• My choice if BEC is the biggest concern.

2. Microsoft Defender for Office 365 — best if you're already Microsoft 365-heavy

• Microsoft's system uses LLMs, SLMs and machine learning to classify phishing, malware and BEC.
• Much more economical if you're already licensed for the appropriate Microsoft security stack.
• I'd generally start here before buying another product if you're a Microsoft 365 organization, then test whether it is actually catching your hardest BEC cases.

3. Proofpoint — strong enterprise alternative

• Particularly worth considering for large enterprises with extensive compliance, data-loss prevention and security-operations requirements.
• I'd put it on the shortlist alongside Abnormal for a serious enterprise evaluation.

The important distinction

For ordinary phishing, Microsoft Defender can be very good.

For BEC, I would specifically test vendors against scenarios like:

"The CFO emails the controller from a legitimate compromised account and asks for a $180,000 wire transfer." There may be no malicious link, attachment, spoofed domain, or authentication failure. That's exactly where behavioral/contextual systems such as Abnormal are designed to have an advantage.

And this is becoming more important: Microsoft researchers are currently seeing attackers use techniques such as invisible Unicode characters to evade conventional filtering and AI processing.

Bottom line: Abnormal AI if you want the strongest dedicated AI/BEC layer; Microsoft Defender for Office 365 if you want the best integrated value in a Microsoft 365 environment.

If you tell me your company size + Microsoft 365 vs Google Workspace + approximate annual security budget, I can give you a much more specific recommendation and a 3-vendor bake-off scorecard.

For stopping phishing and business email compromise (BEC), the “best” AI tool depends on your email platform, company size, and whether you need a replacement gateway or an AI layer on top of existing protection. The strongest options today are:

My typical recommendation by scenario

• Small or mid-size company on Microsoft 365 or Google Workspace: Start with built-in protection (Microsoft Defender or Google protections), then add Abnormal Security if BEC is your main concern. Behavioral AI is especially useful against “fake CEO,” vendor impersonation, and payment-change scams that often contain no malware.
• Enterprise, finance, healthcare, government, or highly regulated environments: Evaluate Proofpoint and Abnormal Security side-by-side. Proofpoint is often favored for broad security controls and compliance needs; Abnormal is often favored for AI-driven BEC detection.
• Microsoft 365 E5 customers: Make sure you are getting full value from Defender first, including configuration hardening, anti-phishing policies, MFA, conditional access, and user reporting workflows. A third-party AI layer may still help with advanced BEC.

A strong anti-BEC stack usually includes:

• AI email analysis (Abnormal, Proofpoint, or Defender)
• MFA with phishing-resistant methods where possible
• DMARC/SPF/DKIM configured correctly
• Payment/vendor-change verification procedures
• Employee phishing reporting and rapid mailbox remediation

If you tell me your environment (Microsoft 365, Google Workspace, or on-prem Exchange) and approximate size (<100, 100–1,000, 1,000+ users), I can narrow it down to the best fit.

There is no single "best" AI tool for every organization because modern AI-driven phishing and Business Email Compromise (BEC) leverage hyper-personalized text, no malicious links, and zero-day pretexts that easily slip past legacy secure email gateways (SEGs).

Instead, the market splits into AI-native behavioral platforms (which excel at catching sophisticated BEC without payloads) and heavyweight enterprise suites (which combine AI with massive global threat intelligence).

The top-performing AI email security solutions categorized by their specific strengths include:

1. Best for Pure Behavioral & BEC Detection (AI-Native)

• Abnormal Security : Widely considered a gold standard for stopping Business Email Compromise and internal account takeovers. Because it integrates natively via API rather than sitting as a traditional email gateway, it builds a deep behavioral baseline of normal communication patterns for every single identity in the company. If an attacker compromises a vendor or mimics an executive using flawless AI-generated phrasing, Abnormal spots the slight anomaly in behavior, tone, or financial request context even if the sending domain looks clean.

2. Best for Inline Cloud-Email Security & Remediation

• Check Point Harmony Email & Collaboration (Avanan) : Exceptional at intercepting threats inline before they hit the inbox for Microsoft 365 and Google Workspace. It scans internal emails (critical for catching lateral BEC movement) and collaboration apps like Slack and Microsoft Teams. Its automated remediation workflows dramatically reduce the manual strain on security operations teams.

3. Best for Autonomous & Unsupervised Machine Learning

• Darktrace / EMAIL : Uses self-learning AI that doesn't rely on prior signatures or historical training sets of "known bad" attacks. It forms an "understanding of self" for the organization, meaning it can spot brand-new, never-before-seen social engineering pretexts or anomalous links (like unusual Dropbox or SharePoint lures) in real-time and neutralize them instantly.

4. Best Traditional Incumbents with Heavyweight AI Engines

• Proofpoint & Mimecast : If your organization requires a massive, enterprise-grade Secure Email Gateway combined with security awareness training, archiving, and DMARC management, these legacy leaders have heavily retrofitted their platforms with advanced natural language processing (NLP) and behavioral AI engines to combat modern spear-phishing.

Summary Recommendation:

• Choose an API-native ICES (Integrated Cloud Email Security) tool like Abnormal or Check Point/Avanan if you already use Microsoft 365 or Google Workspace native security and want a specialized AI layer that sits behind it to catch advanced BEC.
• Choose an all-in-one platform like Proofpoint or Mimecast if you need a comprehensive compliance, archiving, and gateway ecosystem.

To help narrow down the ideal choice, tell me:

• What email infrastructure do you use (Microsoft 365, Google Workspace)?
• Do you prefer an API-only overlay or a full traditional gateway replacement?
• Have you recently experienced a specific type of attack (e.g., vendor email fraud, executive impersonation)?

There is no single "best" AI tool for every organization because modern anti-phishing and Business Email Compromise (BEC) solutions generally fall into two different philosophical approaches: API-native behavioral AI (which excels at catching zero-day social engineering by learning normal communication patterns) and Secure Email Gateways / Hybrid Platforms (which offer deep traditional infrastructure control alongside modern AI).

The top-rated AI-driven email security tools on the market are categorized below by their primary strengths:

• Abnormal AI — Best for Behavioral AI & BEC Detection
  • Strengths: Abnormal is an API-native, AI-first platform that builds behavioral baselines for every identity in your cloud email environment (Microsoft 365 or Google Workspace). Because it doesn’t rely solely on known malicious indicators or traditional signatures, it is exceptionally good at spotting zero-payload attacks, vendor email compromise, and sophisticated executive impersonation where no malicious link or attachment exists.
• Check Point Harmony Email and Collaboration (Avanan) — Best Inline API-Native Protection
  • Strengths: Avanan sits natively via API but uses patented inline architecture to block malicious emails before they hit the inbox, even scanning internal-to-internal emails and collaboration tools like Slack or Microsoft Teams. It deploys in minutes and acts as a strong secondary layer that catches what native Microsoft or Google security filters miss.
• Proofpoint Email Security — Best for Enterprise Scale & Threat Intelligence
  • Strengths: As a dominant enterprise incumbent, Proofpoint combines massive global threat telemetry with advanced machine learning, sandboxing, and URL rewriting. It is ideal for large organizations that require rigorous compliance, deep data loss prevention (DLP), and a robust, battle-tested security gateway.
• Darktrace / EMAIL — Best Autonomous Response AI
  • Strengths: Part of Darktrace’s ActiveAI Security Platform, Darktrace/EMAIL understands an organization's "pattern of life" dynamically. It doesn't just block incoming phishing on arrival; its autonomous response technology can isolate compromised accounts and neutralize lateral movement inside the messaging ecosystem in real time.
• IRONSCALES — Best for Automated Incident Response & Crowd-Sourced AI
  • Strengths: IRONSCALES blends automated AI threat detection (via its engine, Themis) with collaborative, community-driven incident response. It empowers security teams to remediate phishing across all inboxes globally with one click once an anomaly is identified.

To help narrow down which tool fits your environment best, let me know:

• Are you using Microsoft 365, Google Workspace , or a hybrid setup?
• Roughly how many inboxes does your organization protect?
• Have you recently experienced a specific type of attack (like vendor impersonation or credential harvesting)?

The “best” AI tool for stopping phishing and business email compromise (BEC) depends on your email platform, company size, and whether you need a replacement gateway or an AI layer on top of existing email security. The strongest options today are:

My practical recommendation

• Microsoft 365 + under ~5,000 users: Start with Microsoft Defender for Office 365, then add an AI BEC specialist like Abnormal Security if you are still seeing impersonation or invoice fraud attempts.
• High-risk company (finance, legal, executives frequently targeted): Consider Proofpoint or a layered approach with Proofpoint + an AI behavioral layer.
• Small business: A well-configured Microsoft/Google security stack plus phishing training, MFA, and payment-verification procedures may provide the best cost-to-risk ratio before adding enterprise tools.

One important point: AI email security is strongest against BEC, because those attacks often have no malware, bad links, or obvious indicators. The AI has to understand relationships and intent (“Why is the CFO suddenly asking for a wire transfer?”), not just scan attachments.

If you tell me:

1. Microsoft 365, Google Workspace, or another email system?
2. Number of employees/mailboxes?
3. Your budget range?

…I can narrow it to the best 1–2 choices.

If your main goal is stopping phishing and business email compromise (BEC), my top pick today is Abnormal AI—especially for organizations already using Microsoft 365 or Google Workspace.

My ranking

1. Abnormal AI — best for sophisticated BEC

• Uses behavioral AI to build a baseline for each employee and vendor, rather than relying mainly on signatures or known malicious URLs.
• Particularly strong against CEO/CFO impersonation, vendor fraud, compromised accounts, thread hijacking, and payload-less BEC—attacks that can pass SPF/DKIM/DMARC and look completely legitimate.
• It can automatically remove malicious messages after detection and remediate attacks across mailboxes.
• Best choice if BEC/payment fraud is your biggest concern.

2. Microsoft Defender for Office 365 — best value if you're already on Microsoft 365

• Microsoft has substantially strengthened its AI/ML-based email threat classification, including specific classification for BEC and impersonation.
• Defender includes impersonation protection, mailbox intelligence, campaign analysis, and automated remediation such as Zero-hour Auto Purge.
• Best choice if you want strong protection without adding another email-security vendor.

3. Abnormal + Microsoft Defender — strongest combination for high-risk organizations

• Defender provides the Microsoft-native security stack.
• Abnormal adds behavioral analysis specifically designed to catch attacks that get through conventional email controls.
• This is the combination I'd investigate for a company where one successful fraudulent wire/payment could cost hundreds of thousands or millions of dollars.

The important distinction

A lot of products say "AI phishing protection," but BEC is a different problem.

A traditional phishing filter might ask:

"Does this email contain a malicious URL or attachment?" Modern BEC can instead look like:

"Hi Sarah, I'm traveling today. Please send the $185,000 payment to this new account." There may be no attachment, no malicious URL, and no authentication failure. The attacker may even be using a compromised vendor's real mailbox. That's exactly the class of attack behavioral systems such as Abnormal are designed to identify.

So if you tell me your environment (Microsoft 365 vs. Google Workspace, approximate number of employees, and whether you're primarily worried about phishing, wire fraud/BEC, or both), I can give you a specific 3–5 product shortlist with estimated cost, deployment difficulty, and which one I'd buy.

There is no single "best" tool for every organization, as the right choice depends on your existing infrastructure (e.g., Microsoft 365 vs. Google Workspace) and company size. However, the market has largely shifted toward AI-native behavioral platforms because traditional Secure Email Gateways (SEGs) struggle with modern, highly personalized, and AI-generated Business Email Compromise (BEC).

The top-rated AI-powered email security platforms excelling at stopping phishing and BEC include:

• Abnormal Security: Widely recognized as a leader in AI-native behavioral email security. Instead of relying on traditional reputation lists or signatures, it builds a baseline of normal communication behavior for every identity in the organization. It excels at catching sophisticated, zero-day BEC and spear-phishing because it recognizes anomalous context (like a sudden shift in tone or a rogue wire-transfer request) even if the sender's account isn't technically compromised.
• Proofpoint Email Protection: Powered by its NexusAI engine, Proofpoint remains an enterprise heavyweight. It combines massive global threat intelligence with deep behavioral analysis. It is exceptionally strong at supply chain impersonation defense and handling complex compliance or large enterprise requirements.
• Darktrace / EMAIL: Uses self-learning AI to understand the "pattern of life" for each user and organization. It stands out for its ability to analyze fast-moving, novel attacks across the entire collaboration ecosystem and autonomously remediate threats with minimal human intervention.
• IRONSCALES: Highly favored by mid-market companies and Managed Service Providers (MSPs). It utilizes a crowdsourced threat intelligence model combined with localized AI to detect and automatically remove malicious emails from inboxes, alongside strong built-in automated incident response and human-layer simulation training.
• Avanan (by Check Point): Unique because it deploys via API inline post-delivery or pre-delivery inside cloud email environments like Microsoft 365. Its machine-learning engine reads internal and external communication threads, making it very effective at catching lateral internal phishing and BEC that slip past traditional perimeter gateways.

Which one should you pick?

• Choose Abnormal Security or Avanan if you are heavily cloud-based (Microsoft 365/Google Workspace) and want an API-driven, behavior-first layer that doesn't bottleneck mail flow.
• Choose Proofpoint if you are a massive enterprise requiring rigid compliance alongside elite threat intelligence.
• Choose IRONSCALES if you want an agile, highly automated platform that scales smoothly for mid-sized teams.

To help narrow down the best fit, tell me:

• What email platform do you use (Microsoft 365, Google Workspace, hybrid)?
• Roughly how many employees are in your organization?
• Are you looking for an API-based cloud solution or a traditional gateway?