Best tools · AI detectionVictor TräffWritten by Victor Träff · Security expert and co-founder, Sentaro Reviewed

11 best AI email security tools (2026)

The best AI email security for EU teams on Microsoft 365 and Google Workspace in 2026 is Sentaro, whose proprietary engine, Vord, scores the intent, sender identity and relationship history of every message before interaction, shows its reasoning on every verdict in the console, and costs a published $6 per protected account per month. The other strong options are Abnormal AI, Microsoft Defender for Office 365 as the native baseline, Darktrace / EMAIL and Check Point Harmony Email & Collaboration. We ranked 11 tools on what each vendor documents its AI doing, as of 21 October 2026.

  • 11 tools ranked
  • Vendor AI claims quoted
  • Weighted, sourced method
  • Last verified 21 October 2026
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Our recommendation

Sentaro is the best AI email security for EU organizations on Microsoft 365 and Google Workspace: its engine reads intent (payment redirects, secrecy, artificial deadlines), sender infrastructure and thread history rather than keywords, assumes attack content is AI-written, explains every verdict in the console so admins can audit it, and is live in four minutes over API at a published $6 per protected account per month. Its public DPA lists its subprocessors, including a third-party AI provider, Anthropic, for limited threat-signal analysis. Sentaro publishes this list and ranks itself first; scores use the method below and public vendor documentation as of 21 October 2026.

Why Sentaro wins
detection built for payload-free, AI-written fraud, reasoning attached to each verdict, OAuth and AI-tool discovery in the same platform, and a price and DPA you can read before talking to anyone.
Know what you are buying
“AI” covers very different things here: per-user behavioral baselines, LLM content analysis, ensembles of classic ML engines, and AI agents that write detection rules. The table below quotes each vendor.
Consider another tool only if
you need account-takeover detection live today (Sentaro’s Behavioral vector is Q4 2026), certifications already issued, or a gateway, archive or training suite.

Quick picks

  • Best overall for EU teamsSentaro Our pickIntent and relationship scoring, reasoning on every verdict, $6 per account per month, hosted in Sweden.
  • Best for large enterprisesAbnormal AIBehavioral baselines per employee and vendor, account takeover, ISO 42001 among its certifications.
  • Best native baselineMicrosoft Defender for Office 365Mailbox intelligence and impersonation protection already in Business Premium and E3.
  • Best per-organization modelDarktrace / EMAILLearns from your own organization, not a shared cross-customer model, per Darktrace.
  • Best for transparent rulesSublime SecurityOpen detection rules plus AI agents that write and backtest them.
  • Best explainable verdicts in a suiteBarracuda Email ProtectionIts Bailey assistant explains detection decisions in plain language.

At a glance

What we compared
Email security that uses AI or machine learning to detect phishing, BEC and fraud, judged on what each vendor documents its AI doing
Tools ranked
11: Sentaro, Abnormal, Defender for Office 365, Darktrace, Check Point, Sublime, IRONSCALES, Barracuda, Proofpoint, FortiMail Workspace Security, Hornetsecurity (Vade)
Audience
EU organizations on Microsoft 365 or Google Workspace, lean IT, often regulated
Method
Seven weighted criteria, scored 0–10 from public documentation; vendor detection-rate claims are not used
Last verified
21 October 2026 (vendor pages accessed 18–21 October 2026)
Written by
Sentaro, which makes one of the tools ranked here

AI email security tools compared

One row per tool, in rank order. The AI column quotes or closely paraphrases each vendor; we did not test the models.

CapabilityScoreWhat the vendor says its AI doesDeploymentPublic priceBest for
Sentaro (our pick)[3]8.2Proprietary signals, expert algorithms and a family of models (encoders, decoders, reasoning) reach one explained verdictAPI, no MX change$6 per account/month; first account freeEU teams on Microsoft 365 and Google Workspace
Abnormal AI[4]7.4Behavioral AI baselines every employee and vendor and flags deviationsAPI, no MX changeQuoteLarge enterprises
Defender for Office 365[6]7.1Mailbox intelligence (contact graph) for impersonation; Safe Links and Safe AttachmentsNative to Exchange OnlinePlan 1 $2, Plan 2 $5 per user/monthEvery Microsoft 365 tenant, as the baseline
Darktrace / EMAIL[9]6.8Learns from your own organization’s activity, not a shared cross-customer modelAPI, or API plus journalingQuoteExisting Darktrace customers
Check Point Harmony Email[11]6.850+ AI engines plus sandboxing and click-time URL checksAPI with inline preventionQuoteEmail plus many SaaS apps
Sublime Security[13]6.6Detection-as-code plus AI agents that triage reports and write rulesAPI; managed or self-hostedFirst 100 mailboxes freeSOC teams that write rules
IRONSCALES[16]6.5Adaptive AI with per-mailbox baselines and crowdsourced intelligenceAPI at mailbox levelQuoteSMBs and MSPs
Barracuda[18]6.4Multi-model AI on intent and identity anomalies; Bailey explains decisionsAPI-first, no MX changeQuoteSuite buyers who want explanations
Proofpoint[20]6.2Multi-model behavioral AI tied to Nexus threat intelligenceAPI or inline gatewayQuoteLarge enterprises with add-ons
FortiMail Workspace Security[22]5.7ML, large language models, heuristics and optical scanningAPI (ICES); gateway in FortiMailQuoteFortinet customers
Hornetsecurity (incl. Vade)[23]5.5AI-based ATP; Vade: AI learning from 1.4 billion mailboxes, computer vision, NLPMX, API or hybridQuote via partnersMSP-managed Microsoft 365

Editorial scores using the criteria and weights below; based on public documentation, not lab tests. Last verified 21 October 2026.

  • Yes
  • Partial
  • No
  • On roadmap
  • Paid add-on
  • Not publicly documented
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What “AI email security” actually means

Almost every email security vendor now says AI. Underneath, four different designs are on sale, and they catch different things. Knowing which one you are buying matters more than the label.

ApproachWhat it looks atStrong againstVendors here (their description)
Per-user or per-organization behavioral baselinesWho normally writes to whom, when, and howImpersonation and account misuse that looks unusual for that sender or recipientAbnormal, Darktrace, IRONSCALES
Intent and content analysis, including language modelsWhat the message asks for: payment changes, credentials, secrecy, urgencyPayload-free BEC and AI-written lures with no link or attachmentSentaro, FortiMail (LLM named), Vade (NLP)
Ensembles of ML engines with sandboxing and URL analysisLinks, files, sender reputation, many classifiers combinedMalware, credential-harvest links, QR-code luresCheck Point, Proofpoint, Barracuda, Defender
Detection-as-code with AI agentsRules you can read and edit; agents that draft and test themTeams that want to see and tune every detectionSublime

Most products mix these. Sentaro’s Vord engine, for example, deconstructs each event into tens to over a hundred signals, sends them to expert algorithms (URLs, attachments, typosquats, identities) and, when called for, to larger reasoning models, and returns one verdict with its reasoning. Abnormal combines identity, behavioral and content signals. The question for a buyer is which signals the product weighs most, and whether it can show you why it decided.

Why AI-written phishing changes the criteria

Generative AI removes the spelling mistakes and odd phrasing that older filters and trained users relied on, and lets attackers write a convincing request in any language. The tell is no longer in the wording; it is in the request (a new bank account, a gift-card purchase, a password reset) and in the relationship (a supplier who has never asked for this, a reply injected into a real thread). That is why this ranking gives the most weight to detection of payload-free, intent-based fraud.

How we evaluated AI email security tools

We scored what each vendor documents its AI doing, not how often it says “AI”. Detection of payload-free, AI-written fraud carries the most weight, followed by whether verdicts can be explained and how customer data is used to run and train models. Maturity counts too; that is where the larger vendors lead.

CriterionWeightWhy it matters
Detection of payload-free and AI-written lures30%Does the AI read intent, relationship and thread context, so it can flag a well-written request with no link or attachment? Vendor-compromise detection scores highest.
Explainable verdicts15%Can an admin see why a message was flagged, in words, and audit the decision rather than trust a score?
Data use and model transparency15%Where models run, whether customer mail trains shared or third-party models, and whether the DPA and subprocessors are public.
Time to value10%How fast it protects: API setup time, and whether baselines are built from existing mailbox history or need a learning period.
Published price10%A published price lets you compare cost per mailbox without a sales cycle.
Coverage beyond the inbox10%AI-driven attacks move to Teams, Slack and OAuth consent. Coverage of collaboration apps and connected apps counts here.
Maturity and independent validation10%Certifications issued, account-takeover coverage, analyst and peer recognition, years in market.

Editorial scores using the criteria and weights above; based on public documentation, not lab tests. Vendor detection-rate claims were not used. Sentaro’s roadmap features (Identity, Behavioral, Q4 2026) score as not available.

The 11 best AI email security tools, ranked

Highest score first. Each summary describes the AI in the vendor’s own words, attributed; the scores judge what that AI is documented to do.

  1. Sentaro

    Our pickOverall score: 8.2out of 10

    Best for: EU teams on Microsoft 365 and Google Workspace that want AI built for payload-free fraud, with reasoning they can audit and a published price.

    Sentaro’s proprietary engine, Vord, deconstructs each event into proprietary signals, runs them through expert algorithms and a family of models (encoders, decoders and reasoning models), and reaches one verdict with its reasoning attached, before the recipient interacts. The Message vector reads intent and language (payment redirects, credential prompts, secrecy and artificial deadlines, “not keyword lists”), sender identity and infrastructure, and relationship and thread context, including suppliers that suddenly change bank details. Sentaro says Vord assumes attack content is AI-written. Relationship baselines come from existing mailbox history rather than a long learning period. Verdicts come from Sentaro’s own engine; its DPA lists Anthropic (Claude) as a US subprocessor for limited threat-signal analysis, with no training on customer data.[3]

    Detection of payload-free and AI-written lures
    8.0
    Explainable verdicts
    9.0
    Data use and model transparency
    8.0
    Time to value
    10.0
    Published price
    10.0
    Coverage beyond the inbox
    9.0
    Maturity and independent validation
    3.0

    Pros

    • Built for intent-based, payload-free fraud, including vendor compromise and thread hijacking.
    • Every verdict shows its reasoning in the console.
    • Baselines from existing mailbox history; live in four minutes over API with no MX change.
    • Discovers AI tools and OAuth grants in the same platform; published price.

    Cons

    • Per-user behavioral baselines and account-takeover detection (Behavioral vector) reach general availability in Q4 2026.
    • SOC 2 and ISO 27001 certification in progress; no third-party tests or analyst coverage yet.
    • Its Global Model learns from data derived from all customers (designed not to reproduce one customer’s raw content to another), which some buyers will want to review in the DPA.
    Pricing
    $6 per protected account per month or $68 per year; first account free. Prices in USD.
    Deployment
    API via the Microsoft 365 and Google Workspace admin SDKs; no MX change, no agents
    Platforms
    Microsoft 365, Google Workspace; Slack and Teams listed as channels
    Hosting
    Hosted in Sweden on Microsoft Azure; subprocessors listed in the DPA
    More on Sentaro

  2. Abnormal AI

    Overall score: 7.4out of 10

    Best for: Large enterprises that want behavioral AI across email, identity and SaaS, with certifications already issued.

    Abnormal describes behavioral AI that builds a baseline for every employee and vendor and flags deviations using identity, behavioral and content signals, reading authentication events, calendar activity and internal threads. It deploys over API with no MX change (“Deploy in 60 seconds via API”) and sells Account Takeover Protection, AI Phishing Coach and AI security products alongside. Its trust center lists ISO 27001, ISO 27701 and ISO 42001 certificates, a SOC 2 report and FedRAMP Moderate, and its public subprocessor list names Azure OpenAI Service for AI-enabled functionality and AWS hosting in the US or the EU (Ireland), set by subscription. Prices are not published.[4]

    Detection of payload-free and AI-written lures
    9.0
    Explainable verdicts
    5.0
    Data use and model transparency
    7.0
    Time to value
    9.0
    Published price
    3.0
    Coverage beyond the inbox
    7.0
    Maturity and independent validation
    10.0

    Pros

    • Behavioral baselines for employees and vendors.
    • ISO 42001 AI management certification among many.
    • Account takeover and SaaS coverage.

    Cons

    • No public prices.
    • EU (Ireland) hosting is a subscription choice; the US is the other listed location.
    • How verdicts are explained to admins is not documented publicly.
    Pricing
    Quote-based
    Deployment
    API (ICES), no MX change
    Platforms
    Microsoft 365, Google Workspace
    Hosting
    AWS in the US or EU (Ireland), by subscription (subprocessor list)
    Sentaro vs Abnormal Security Vendor site

  3. Microsoft Defender for Office 365

    Native baselineOverall score: 7.1out of 10

    Best for: Every Microsoft 365 tenant, as the layer under any AI add-on.

    Microsoft does not market Defender for Office 365 mainly as AI, but it documents learned protections: mailbox intelligence uses each user’s contact graph to spot impersonation, alongside user and domain impersonation protection, Safe Attachments detonation and Safe Links (including QR-code attacks, per Microsoft’s June 2026 blog). Plan 2 adds Threat Explorer, campaigns and automated investigation and response. Plan 1 is in Business Premium and rolling out to E3 from 17 June 2026.[6]

    Detection of payload-free and AI-written lures
    5.0
    Explainable verdicts
    6.0
    Data use and model transparency
    8.0
    Time to value
    9.0
    Published price
    10.0
    Coverage beyond the inbox
    6.0
    Maturity and independent validation
    10.0

    Pros

    • Already licensed in most business tenants.
    • Covers Teams, SharePoint and OneDrive.
    • Plan 2 adds investigation and automated response.

    Cons

    • No documented intent model for payload-free fraud.
    • OAuth app governance is a separate product.
    • Microsoft 365 only.
    Pricing
    Plan 1 $2, Plan 2 $5 per user/month, paid yearly; included in Business Premium, E3 (P1) and E5 (P2)
    Deployment
    Native to Exchange Online
    Platforms
    Microsoft 365
    Hosting
    EU Data Boundary for EU/EFTA tenants (Multi-Geo excluded)
    Sentaro vs Microsoft Defender for Office 365 Vendor site

  4. Darktrace / EMAIL

    Overall score: 6.8out of 10

    Best for: Organizations already using Darktrace that want a behavioral model trained on their own traffic.

    Darktrace describes behavioral AI that “learns from your own organization’s activity and users, not a shared cross-customer model”, with “no signatures to maintain”. For Microsoft 365 it recommends API plus journaling, which receives a copy in transport before the inbox; API-only works post-delivery. It names BEC, adds Identity Detection & Response (terminate sessions, force re-authentication) and covers Teams, Zoom and Slack. Google Workspace support was not confirmed in our sources, and prices are not published.[9]

    Detection of payload-free and AI-written lures
    9.0
    Explainable verdicts
    5.0
    Data use and model transparency
    7.0
    Time to value
    5.0
    Published price
    3.0
    Coverage beyond the inbox
    7.0
    Maturity and independent validation
    8.0

    Pros

    • Model trained on your own organization only, per Darktrace.
    • Identity response: session termination and forced re-authentication.
    • Teams, Zoom and Slack coverage.

    Cons

    • Google Workspace support not confirmed.
    • No public prices or setup time.
    • Best value inside the wider Darktrace platform.
    Pricing
    Quote-based
    Deployment
    API, or API plus journaling for Microsoft 365
    Platforms
    Microsoft 365; Teams, Zoom, Slack
    Hosting
    Not publicly documented
    Vendor site

  5. Check Point Harmony Email & Collaboration

    Overall score: 6.8out of 10

    Best for: Organizations that want many detection engines inline via API across email and collaboration apps.

    Check Point describes “50+ AI engines” combined with URL emulation, sandboxing, attachment sanitization (CDR) and click-time URL protection. It connects over API with no MX change and can enforce inline, before mail reaches the inbox. BEC is named; account takeover and shadow IT detection are in every tier, and Teams, Slack, OneDrive, SharePoint, Google Drive, Box and Dropbox are covered. The admin guide lists an Ireland data-residency region.[11]

    Detection of payload-free and AI-written lures
    7.0
    Explainable verdicts
    5.0
    Data use and model transparency
    6.0
    Time to value
    9.0
    Published price
    3.0
    Coverage beyond the inbox
    9.0
    Maturity and independent validation
    9.0

    Pros

    • Inline prevention via API.
    • Broadest collaboration-app coverage here.
    • Account takeover in every tier.

    Cons

    • No public prices.
    • How the engines reach a verdict is not explained publicly.
    • Archiving, DMARC and training are add-ons.
    Pricing
    Quote-based; four tiers
    Deployment
    API with configurable inline prevention
    Platforms
    Microsoft 365, Google Workspace and major collaboration apps
    Hosting
    Regions include Ireland (EMEA), per the admin guide
    Sentaro vs Check Point Harmony Email Vendor site

  6. Sublime Security

    Overall score: 6.6out of 10

    Best for: Security teams that want to read every detection and let AI agents help write them.

    Sublime’s detection is code: rules in its Message Query Language, with an open library on GitHub that includes BEC, QR-code and lookalike-domain rules. Two AI agents sit on top: ASA, an autonomous security analyst that triages user reports, and ADÉ, an autonomous detection engineer that writes and backtests rules, now generally available for Enterprise. It connects to Microsoft 365, Google Workspace and IMAP over API, managed or self-hosted in your own AWS or Azure; the managed cloud is free for the first 100 mailboxes.[13]

    Detection of payload-free and AI-written lures
    7.0
    Explainable verdicts
    9.0
    Data use and model transparency
    7.0
    Time to value
    5.0
    Published price
    7.0
    Coverage beyond the inbox
    4.0
    Maturity and independent validation
    5.0

    Pros

    • Fully readable detection logic.
    • AI agents that draft and backtest rules.
    • Free tier and self-hosting.

    Cons

    • Assumes staff who will work with rules.
    • Email only.
    • Certifications not verified.
    Pricing
    Managed cloud free for the first 100 mailboxes; Enterprise quote-based
    Deployment
    API; managed cloud or self-hosted
    Platforms
    Microsoft 365, Google Workspace, IMAP
    Hosting
    Managed-cloud regions include EU (Dublin) and UK (London); or self-host in your own AWS or Azure region
    Sentaro vs Sublime Security Vendor site

  7. IRONSCALES

    Overall score: 6.5out of 10

    Best for: SMBs and MSPs that want adaptive AI plus phishing simulation from one vendor.

    IRONSCALES describes adaptive AI with behavioral baselines for every mailbox, combined with threat intelligence crowdsourced from its customer community’s reports, and automated post-delivery remediation. It deploys over API “in minutes, no MX changes”, adds deepfake protection for Microsoft Teams meetings, and in 2026 introduced agents for red teaming, phishing SOC work and simulation. Tiers are published; prices are on quote.[16]

    Detection of payload-free and AI-written lures
    8.0
    Explainable verdicts
    5.0
    Data use and model transparency
    5.0
    Time to value
    9.0
    Published price
    4.0
    Coverage beyond the inbox
    6.0
    Maturity and independent validation
    7.0

    Pros

    • Per-mailbox baselines plus community intelligence.
    • Teams deepfake protection.
    • Simulation and training bundled.

    Cons

    • Prices on quote only.
    • Model data-use terms not documented; the subprocessor list names AWS in both the USA and Germany without saying who is hosted where.
    • Account takeover only in higher tiers.
    Pricing
    Quote-based; tiers published
    Deployment
    API at mailbox level
    Platforms
    Microsoft 365, Google Workspace; Teams
    Hosting
    Subprocessor list names AWS in the USA and AWS Europe (Germany)
    Sentaro vs IRONSCALES Vendor site

  8. Barracuda Email Protection

    Overall score: 6.4out of 10

    Best for: Buyers who want a full email suite whose AI explains its decisions.

    Barracuda IQ is described as multi-model AI analysing intent and identity anomalies, using 100+ global threat feeds, with Behavioral Account Takeover Detection. Its “Bailey” assistant is described as explainable AI that explains detection decisions in plain language. It is API-first with no MX change and lists DMARC reporting, encryption and DLP in every plan, with backup, archiving and training in higher plans.[18]

    Detection of payload-free and AI-written lures
    7.0
    Explainable verdicts
    8.0
    Data use and model transparency
    5.0
    Time to value
    8.0
    Published price
    3.0
    Coverage beyond the inbox
    4.0
    Maturity and independent validation
    8.0

    Pros

    • Explainable verdicts in plain language.
    • Behavioral account-takeover detection.
    • Suite extras in the same plans.

    Cons

    • No public prices.
    • Impersonation Protection and Incident Response are listed in US regions only; model data use not documented.
    • Little coverage beyond email.
    Pricing
    Quote-based; three plans
    Deployment
    API-first, no MX change
    Platforms
    Microsoft 365, Google Workspace
    Hosting
    Trust center: Email Gateway Defense in Frankfurt and London regions; Impersonation Protection and Incident Response in US regions
    Sentaro vs Barracuda Vendor site

  9. Proofpoint

    Overall score: 6.2out of 10

    Best for: Large enterprises that want behavioral AI backed by very large threat intelligence and many add-ons.

    Proofpoint describes multi-model behavioral AI tied to its Nexus threat intelligence, “informed by thousands of threat campaigns and trillions of emails, URLs, and attachments”, plus URL and attachment sandboxing. It names BEC and supplier threats, deploys via API (Microsoft Graph, “in 48 hours”) or inline, and sells account takeover, DMARC, DLP, archiving and awareness training as add-ons.[20]

    Detection of payload-free and AI-written lures
    8.0
    Explainable verdicts
    5.0
    Data use and model transparency
    5.0
    Time to value
    6.0
    Published price
    3.0
    Coverage beyond the inbox
    4.0
    Maturity and independent validation
    10.0

    Pros

    • Very large threat-intelligence base.
    • API or inline deployment.
    • Widest add-on range.

    Cons

    • Most capabilities are add-ons.
    • No public prices.
    • Some email data may be processed and stored in the US even for EU tenants, per its API privacy sheet.
    Pricing
    Quote-based
    Deployment
    API (Microsoft Graph) or inline gateway
    Platforms
    Microsoft 365, Google Workspace
    Hosting
    Core Email Protection API: EU or US data centre; some processing and storage in the US (privacy sheet, July 2026)
    Sentaro vs Proofpoint Vendor site

  10. FortiMail Workspace Security

    Overall score: 5.7out of 10

    Best for: Fortinet customers that want LLM-based detection plus browser and collaboration coverage with managed response.

    Fortinet bought Perception Point in December 2024 and sells it as FortiMail Workspace Security, an ICES product for Microsoft 365 and Google Workspace. Fortinet states its detection uses “machine learning (ML), large language models (LLM), heuristics, and optical scanning”, and Perception Point’s recursive unpacking scans every file and URL. Workspace Security adds browser security, Teams, Slack, Salesforce and Zendesk coverage, and a 24x7 managed incident response service. Prices are on request.[22]

    Detection of payload-free and AI-written lures
    6.0
    Explainable verdicts
    5.0
    Data use and model transparency
    4.0
    Time to value
    5.0
    Published price
    3.0
    Coverage beyond the inbox
    9.0
    Maturity and independent validation
    8.0

    Pros

    • LLM-based detection named explicitly.
    • Browser and collaboration-app coverage.
    • 24x7 managed incident response included.

    Cons

    • No public prices or setup time.
    • Hosting locations not listed.
    • Product name and packaging changed after the acquisition.
    Pricing
    Quote-based
    Deployment
    API (ICES); gateway, VM and appliance options in the wider FortiMail line
    Platforms
    Microsoft 365, Google Workspace; Teams, Slack, Salesforce, Zendesk, browsers
    Hosting
    Not publicly documented
    Vendor site

  11. Hornetsecurity (incl. Vade)

    Overall score: 5.5out of 10

    Best for: MSP-managed Microsoft 365 customers that want AI filtering inside an all-in-one licence.

    Hornetsecurity, owned by Proofpoint since December 2025, sells AI-based advanced threat protection in 365 Total Protection Plan 2 and above, and an “AI Cyber Assistant” (AI Recipient Validation, Teams Protection, AI Email Security Analyst) in Plan 4. It bought Vade in 2024; Vade states its engine “continuously learns from an alliance of more than 1.4 billion protected mailboxes”, with computer vision for phishing and natural language processing for spear phishing. Hornetsecurity states it uses 12 regional data centres, independent of Microsoft’s infrastructure.[23]

    Detection of payload-free and AI-written lures
    6.0
    Explainable verdicts
    5.0
    Data use and model transparency
    6.0
    Time to value
    5.0
    Published price
    3.0
    Coverage beyond the inbox
    5.0
    Maturity and independent validation
    7.0

    Pros

    • AI filtering plus archiving, backup and training in one licence.
    • European data centres (vendor).
    • Vade’s large mailbox telemetry.

    Cons

    • AI detection detail is thin in public material.
    • No public prices.
    • Vade brand being folded into Hornetsecurity and Proofpoint.
    Pricing
    Quote-based, sold through partners
    Deployment
    MX, API or hybrid
    Platforms
    Microsoft 365 (Vade also lists Google Workspace)
    Hosting
    12 regional data centres, independent of Microsoft’s infrastructure (vendor)
    Sentaro vs Hornetsecurity Vendor site

How to choose an AI email security tool

Test it on the attacks AI makes easier

Run a trial in read-only or monitor mode on your own tenant and look for three things in the last 30 days of mail: fraud with no link or attachment (a supplier asking to update bank details, a CEO asking for a quick favour), lures written in your staff’s language with no errors, and replies injected into real threads. These are what generative AI makes cheap, and where AI-based tools should earn their place over your native filtering.

Ask how a verdict is explained

A score without a reason is hard to act on and hard to defend to an auditor. Ask to see a flagged message in the console and the explanation an admin gets. Sentaro shows reasoning on every verdict in the console; Barracuda describes plain-language explanations from Bailey; Sublime’s rules are readable code. For the others, explanation was not documented in the public material we reviewed, so ask for a demo on your own mail.

Ask where the models run and what trains them

  • Does the vendor use third-party AI providers, and are they named in the DPA as subprocessors?
  • Is customer mail used to train a model shared with other customers, and what prevents one customer’s content from surfacing for another?
  • Where is mail content processed and stored, and for how long?
  • Can you opt out of shared-model training, or self-host?

Sentaro answers these in its public DPA: verdicts come from its own engine, Vord; Anthropic (Claude) is listed as a US subprocessor for limited threat-signal analysis, with no training on customer data and no retention beyond processing; and a Global Model trained on data derived from multiple customers is designed and tested not to reproduce one customer’s raw email content to another. Darktrace states its model learns from your organization only. Sublime can be self-hosted.

Do not buy on detection-rate claims

Several vendors publish detection or block rates for their own products. They are measured on their own terms and are not comparable across vendors, so this ranking does not use them. A side-by-side trial on your own traffic, run alongside your current filtering, is the only comparison that holds.

Certification and compliance status

Sentaro’s own status, stated exactly.

SOC 2
In progressNo target date published. Evidence pack on request.
ISO 27001
In progressSentaro says it will announce it the day it is signed, and not before.
Google CASA
Verified API integration
Third-party AI subprocessor
Disclosed in the DPAAnthropic (Claude), US, limited threat-signal analysis; no training on customer data.[2]

Frequently asked questions

What is the best AI email security?

Sentaro, for EU organizations on Microsoft 365 and Google Workspace. Its proprietary engine, Vord, scores intent, sender identity and relationship history before interaction, assumes attack content is AI-written, and shows its reasoning on every verdict in the console. It connects over API in four minutes and costs a published $6 per protected account per month. Abnormal AI is the strongest enterprise alternative. Sentaro publishes this list.

What is AI email security?

Email security that uses machine learning or language models to judge messages, instead of relying only on signatures, blocklists and reputation. In practice it means one or more of: behavioral baselines of who normally writes to whom, analysis of what a message is asking for, ensembles of ML classifiers on links and files, or AI agents that help write and tune detection rules.

Can AI email security detect AI-generated phishing?

It can flag it on signals other than wording. AI-written lures lack the errors older filters relied on, so tools that look at intent (payment changes, credential requests, urgency), sender infrastructure and relationship history are better placed than those that look mainly at links and attachments. No vendor can guarantee detection; test on your own mail.

Is Microsoft Defender for Office 365 AI-based?

Microsoft documents learned protections such as mailbox intelligence, which uses each user’s contact graph to detect impersonation, alongside Safe Links, Safe Attachments and impersonation protection. It does not document an intent model for payload-free fraud or a vendor-compromise feature. Most AI email security tools here run alongside Defender rather than replacing it.

Does AI email security send my email to OpenAI or other LLM providers?

It depends on the vendor; check the DPA’s subprocessor list. Sentaro’s DPA lists Anthropic (Claude) as a US subprocessor for limited threat-signal analysis, with no training on customer data; verdicts come from Sentaro’s own engine. Abnormal’s subprocessor list names Microsoft’s Azure OpenAI Service. Fortinet names large language models in its detection without, in the material we reviewed, naming a provider. Ask every vendor in writing.

How long do behavioral AI tools need to learn before they work?

Vendors differ. Sentaro builds relationship baselines from existing mailbox history rather than requiring a long learning period, and shows historical mail within 15 minutes of connecting. Abnormal states 60-second API deployment, and IRONSCALES “minutes”. Darktrace did not state a setup time in the pages we reviewed. Ask how long until baselines are reliable on your traffic.

Which AI email security tools publish their prices?

Sentaro ($6 per protected account per month, or $68 per year, first account free) and Microsoft Defender for Office 365 (Plan 1 $2, Plan 2 $5 per user per month). Sublime’s managed cloud is free for the first 100 mailboxes. Every other tool on this list is quote-based. Prices in USD, checked 18–21 October 2026.

Sources and method

Sentaro publishes this list and ranks itself first; scores use the method above and public vendor documentation as of 21 October 2026. AI descriptions are each vendor’s own words. Product capabilities change; check each vendor’s current documentation. Trademarks belong to their owners. Corrections: contact Sentaro.

  1. Sentaro pricing
  2. Sentaro Data Processing Agreement and subprocessor list
  3. Sentaro platform: Vord engine and deployment
  4. Abnormal AI: Inbound Email Security (accessed 2026-10-18)
  5. Abnormal AI: Trust center (certifications)
  6. Microsoft Learn: Why do I need Microsoft Defender for Office 365? (accessed 2026-10-18)
  7. Microsoft: Defender for Office 365 pricing (accessed 2026-10-18)
  8. Microsoft Learn: EU Data Boundary (accessed 2026-10-18)
  9. Darktrace: Darktrace / EMAIL (accessed 2026-10-18)
  10. Darktrace blog: Why API + Journaling delivers faster email security for Microsoft 365 (November 2025)
  11. Check Point: Harmony Email & Collaboration (accessed 2026-10-18)
  12. Check Point: Harmony Email & Collaboration admin guide, data residency
  13. Sublime Security docs: Installation (accessed 2026-10-18)
  14. GitHub: sublime-security/sublime-rules detection rules
  15. Sublime Security docs: ADÉ, Autonomous Detection Engineer
  16. IRONSCALES: Home page (accessed 2026-10-18)
  17. IRONSCALES: Pricing (accessed 2026-10-18)
  18. Barracuda: Email Protection (accessed 2026-10-18)
  19. Barracuda: Email Protection plans (accessed 2026-10-18)
  20. Proofpoint: Core Email Protection (accessed 2026-10-18)
  21. Fortinet: FortiMail Workspace Security (formerly Perception Point)
  22. Fortinet: FortiMail Email and Workspace Security (accessed 2026-10-21)
  23. Hornetsecurity: 365 Total Protection (accessed 2026-10-18)
  24. Vade (Hornetsecurity): Email security for Microsoft 365 (accessed 2026-10-21)
  25. Microsoft Tech Community: Defender for Office 365 Plan 1 rolling out to Microsoft 365 E3 (2026-06-17)
  26. Thoma Bravo: Completes acquisition of Darktrace (October 2024)
  27. Abnormal AI: Subprocessors (updated 31 July 2026, accessed 2026-10-21)
  28. Sublime Security docs: Sublime Cloud regions (accessed 2026-10-21)
  29. IRONSCALES: List of current sub-processors (PDF, December 2024; accessed 2026-10-21)
  30. Barracuda Trust Center: Data center locations (accessed 2026-10-21)
  31. Proofpoint: Data privacy information sheet, Core Email Protection API (updated 24 July 2026; accessed 2026-10-21)
RelatedSentaro platform and the Vord engineAI-generated phishingSentaro vs Abnormal AIBest email security for Microsoft 365Best email security for Google WorkspaceSentaro DPA and subprocessorsSentaro pricing

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