Top 12+ Email Security Solutions For Microsoft 365
Discover the top Email Security solutions for Microsoft 365, to protect emails, stop phishing attacks, ransomware and business email compromise.
Written by
Craig MacAlpine
Quick Summary
TitanHQ Email Security adds layered phishing, ransomware, and CEO impersonation defense on top of Microsoft 365’s native filtering, with sandboxing and zero-day protection included as standard rather than paid add-ons. The Bayesian filter requires a training period before false positives settle, and support coverage skews toward European business hours.
IRONSCALES deploys via Graph API without MX record changes, pairing Themis AI with crowdsourced human threat intelligence to catch BEC and credential phishing that Defender misses. Platform coverage is limited to Microsoft 365 and Google Workspace, and the Outlook and Gmail reporting button installation requires manual steps per user.
Material Security extends beyond inbox filtering to protect stored email data, account configuration, and identity, putting MFA in front of historical inbox content so account compromise doesn’t expose years of archived mail. Initial setup carries a learning curve for less technical teams, and the ticketing dashboard still needs polish.
Email security has fragmented into a crowded market where the architecture choice matters as much as the vendor. Secure email gateways, API-based inbox tools, and native platform extensions all claim to stop phishing and BEC, but they approach the problem differently, sit in different parts of the mail flow, and leave different gaps.
The shift to Microsoft 365 and Google Workspace changed the calculus for most organizations. Legacy gateways built for on-premises mail servers now sit in front of cloud platforms they weren’t designed for, processing mail twice and adding latency without access to the behavioral signals that cloud-native tools use. API-based platforms like IRONSCALES, Material Security, and Abnormal AI deploy inside the mailbox rather than in front of it, catching threats after delivery and detecting account compromise in ways perimeter tools can’t.
The market has also split on what email security is for. Tools like TitanHQ and Proofpoint Essentials focus on filtering accuracy and operational simplicity for SMBs and MSPs. Enterprise platforms like Proofpoint Core and Mimecast bundle archiving, eDiscovery, and compliance tooling alongside detection. Behavioral AI tools like Abnormal sit at the higher end on price and focus narrowly on catching what traditional filters miss. Sublime Security takes a different approach entirely, giving technical teams programmable control over detection logic rather than a black-box engine.
We evaluated email security platforms across detection accuracy, deployment model, integration depth with Microsoft 365 and Google Workspace, false positive rates, compliance tooling, and operational overhead. We also reviewed customer experiences across deployed implementations to identify where vendor claims diverge from real-world performance.
This guide gives you the criteria and decision logic to match the right email security platform to your infrastructure, threat model, and team capacity.
TitanHQ Email Security is a multi-layered email filtering platform built for SMBs, MSPs, and enterprises running Microsoft 365. It targets the gaps native Microsoft filtering leaves behind, with a strong focus on phishing, ransomware, and CEO impersonation attempts.
Where TitanHQ earns its keep
We found the filtering itself does the heavy lifting here. It catches considerably more inbound threats than Microsoft 365’s default protections, and the layered approach covers attachment sandboxing, link analysis, and zero-day defenses without pushing those features into a premium tier.
We saw real value in the granular policy controls. You get SPF, DKIM, and DMARC checking, outbound DLP, encryption, mail spooling for continuity, and Office 365 backups in one place. For MSPs managing multiple tenants, that consolidation matters.
What customers are saying
Customers say setup is quick and the Microsoft 365 integration is one of the smoother ones they’ve worked with. The interface gets praise for being approachable, and daily quarantine digests keep end users out of admin tickets.
Some customers have flagged gaps worth weighing. Users have flagged the absence of native threat intelligence enrichment, meaning no inline VirusTotal-style scoring on senders or attachments. A few also say the Bayesian filter needs training time before false positives settle down, and support hours skew toward European time zones.
Who should put this on the shortlist
We think TitanHQ fits SMBs and MSPs that need stronger filtering than Microsoft 365 ships with, without paying Mimecast or Proofpoint pricing. If your team runs lean and you want sandboxing included rather than bolted on, this lands in your range.
Based on our review, larger enterprises with dedicated SOC tooling may want richer threat intel integrations, but for everyone else, the price-to-protection ratio is hard to argue with.
Strengths
- Sandboxing and zero-day protection included as standard, not as paid add-ons
- Strong Microsoft 365 integration with quick deployment for lean IT teams
- Granular policy controls covering inbound, outbound, DLP, and encryption
- Mail spooling and Office 365 backups support business continuity during outages
- Pricing from $1.08 per user makes it accessible for SMBs and MSPs
Cautions
- No native threat intelligence enrichment on sender IPs or attachments in the dashboard
IRONSCALES is a mailbox-level email security platform built for organizations on Microsoft 365 or Google Workspace that want phishing and BEC defense beyond what Defender ships with. It pairs AI detection with crowdsourced human intelligence to catch what native filters miss.
Why the mailbox-level approach matters
We found the Graph API deployment model removes a lot of friction. There’s no MX record change, no mail flow rewiring, and the platform sits inside the mailbox watching for malicious messages in real time, including ones that arrive after delivery.
We saw the combination of Themis AI and human threat intel work well on the harder targets, BEC, credential phishing, and impersonation, where signature-based tools struggle. Built-in awareness training and Teams protection round out a security stack that would normally need three vendors.
What customers are saying
Customers say it catches a meaningful volume of threats that Microsoft 365 with full Defender ATP misses, and the one-click user reporting button is a frequently cited win for reducing SOC workload.
Some customers have flagged the interface as harder to navigate than it should be, with certain settings buried deeper than expected. Users have flagged occasional false positives, manual steps when adding the reporting buttons in Outlook and Gmail, and the absence of an Android admin app as small but real friction points.
Where IRONSCALES fits best
We think IRONSCALES belongs on your shortlist if your environment runs on M365 or Google Workspace and your phishing volume justifies a dedicated mailbox-layer tool. Account compromise risk and Defender gaps are where it pays off.
Based on our review, organizations on other email platforms will need to look elsewhere, but for the M365 and Google Workspace majority, the detection accuracy and user experience hold up well.
Strengths
- Graph API deployment avoids MX record changes and reduces project risk significantly
- Themis AI plus human threat intel catches BEC and phishing Defender misses
- One-click user reporting trims SOC workload and reinforces awareness training
- Built-in phishing simulations and training removes the need for a separate vendor
- Real-time mailbox protection extends to Microsoft Teams alongside email
Cautions
- Limited to Microsoft 365 and Google Workspace, ruling out other email platforms
- Some admin settings could be easier to find, users report
Material Security goes beyond email filtering to protect the full M365 or Google Workspace environment, including inbox data, documents, and account configuration. It targets organizations that have outgrown standalone email security and want identity protection, data governance, and threat response in one platform.
Where Material Security stands apart
We found the data protection angle is what separates Material from typical email security tools. The platform scans historical mail for sensitive content like tax records and invoices, then puts MFA in front of it, so even after an account compromise the attacker can’t walk away with years of stored inbox data.
We saw real value in the account takeover detection. Material watches for 2FA scams, suspicious password resets, and risky config changes, with API deployment in under 30 minutes and no MX record changes.
What customers are saying
Customers say the automatic clustering of similar phishing messages saves the SOC meaningful investigation time, and the “report suspicious message” button gets called out as one of the simpler features to roll out to end users.
Some customers have flagged setup as a learning curve for less technical teams. Users have flagged the ticketing dashboard as needing polish, the metric visuals as not yet interactive, and documentation for advanced configuration as thinner than they’d like.
Who should consider Material
We think Material fits midmarket organizations on M365 or Google Workspace that want their email security to extend into identity, data governance, and configuration without stitching four vendors together. If your concern is what happens after an account is compromised, this is where it earns its place.
Strengths
- Inbox data sits behind MFA, so account compromise doesn't expose years of stored email
- API deployment runs in under 30 minutes with no MX record or mail flow changes
- Account takeover detection covers 2FA scams, password resets, and configuration drift
- Automatic clustering of similar phishing messages reduces SOC investigation time
- Integrates with SIEM, SOAR, and identity tools for centralized visibility and control
Cautions
- Initial setup has a learning curve for teams without dedicated security engineering
- Ticketing dashboard and visualizations still need polish according to admin users
ESET Cloud Office Security extends ESET’s antimalware engine across the full Microsoft 365 stack, covering Exchange Online, Teams, OneDrive, and SharePoint. It targets SMBs and midmarket IT teams that want one tool protecting collaboration apps, not just the inbox.
Why ESET works across the M365 stack
We found the cross app coverage to be the differentiator here. Most email security tools stop at the inbox, but ESET also scans files in OneDrive, messages in Teams, and content shared through SharePoint, applying the same antimalware engine across all of them.
We saw the policy flexibility hold up well. You can configure threat protection at user, group, or organization level, and the native M365 integration deploys quickly without rerouting mail or rewriting MX records.
What customers are saying
Customers say deployment is one of the quicker setups in the category, with spam blocking kicking in within minutes of going live. The dashboard gets praise for being clean and daily management workload is described as light.
Some customers have flagged occasional delays when releasing emails from quarantine. Users have flagged this as the most consistent friction point, though most still rate the platform highly across reliability and ease of use.
Where ESET fits best
We think ESET Cloud Office Security suits SMBs and midmarket organizations on M365 that want one platform covering email, files, and collaboration rather than buying separate tools for each. The management overhead aligns with smaller IT teams.
Based on our review, large enterprises with dedicated SOC tooling and complex policy needs may want a deeper platform, but for the SMB and midmarket segment, ESET provides solid coverage with low operational drag.
Strengths
- Protection extends across Exchange, Teams, OneDrive, and SharePoint, not just email inboxes
- Native M365 integration deploys quickly without MX record changes or mail flow rewrites
- Policy customization works at user, group, and organization level for varied team needs
- Same ESET antimalware engine applies consistently across email, files, and collaboration tools
- Clean dashboard and detailed audit logging make incident tracking and compliance simpler
Cautions
- Occasional delays when releasing emails from quarantine slow legitimate delivery for end users
- Best fit is SMB and midmarket, less so for complex large enterprise environments
- Advanced policy depth may fall short for teams with mature SOC tooling needs
Abnormal AI
Abnormal AI takes a behavioral approach to email security, building a communication baseline for every user and flagging messages that deviate from it. It’s aimed at Microsoft 365 organizations that want to catch BEC, spear phishing, and account takeovers that traditional filtering misses.
Why behavioral AI changes the math
We found the baseline modeling does the heavy lifting on detection. Abnormal analyzes communications against more than 45,000 threat indicators, learning normal patterns for each user, so social engineering that passes technical checks still gets caught when it breaks behavioral norms.
We saw real value in the response automation. When an account is compromised, the platform forces logouts, triggers M365 password resets, and isolates the account, handling remediation that would otherwise queue up as SOC tickets.
What customers are saying
Customers say the false positive rate is meaningfully lower than what they had with traditional gateways like Mimecast and Barracuda, and the API setup completes in under an hour with vendor support. Greymail filtering and reduced triage time come up repeatedly.
Some customers have flagged the AI Phishing Coach module as not yet enterprise ready, citing awkward video and audio quality. Users have flagged interface responsiveness, filter persistence between menus, and the absence of outbound email monitoring as areas that need work.
Where Abnormal earns its budget
We think Abnormal AI fits midmarket and enterprise teams on M365 that have outgrown gateway filtering and need a behavioral layer to catch BEC and account takeover attempts.
Based on our review, pricing sits at the higher end of the category, but for organizations dealing with active phishing pressure, the detection accuracy and remediation automation justify the spend.
Strengths
- Behavioral baseline catches BEC and social engineering that traditional filters routinely let through
- API deployment integrates with M365 in under an hour with no MX record changes
- Auto remediation forces logouts and resets credentials when accounts show signs of compromise
- Greymail filtering and accurate detection reduce SOC time spent on email triage workflows
- URL rewriting and visual warning banners flag suspicious messages without disrupting inbox flow
Cautions
- AI Phishing Coach module isn't polished enough for enterprise rollouts according to admin users
- No outbound email monitoring leaves insider threat detection with a visible coverage gap
- Filter selections don't persist between admin menus, slowing investigation and triage workflows
- Pricing sits at the higher end of the email security category for midmarket buyers
Check Point Harmony Email & Collaboration
Check Point Harmony Email & Collaboration extends Check Point’s threat intelligence to M365 and other cloud collaboration platforms, scanning email, shared files, and internal messages for phishing, malware, and data loss. It targets organizations that want a single tool covering email and collaboration apps together.
What sets Harmony apart in collaboration
We found the cross channel scope to be the differentiator. Harmony watches inbound, outbound, and internal communications, applying URL protection, sandboxing, DLP, and account takeover prevention across email, Outlook, Teams, and shared files from one console.
We saw the ML detection do solid work on subtle phishing attempts that slip past technical checks. The API integration with M365 sits alongside native protections without changing mail flow or MX records, layering defense rather than replacing it.
What customers are saying
Customers say the threat detection runs quietly without slowing daily work, and the dashboard makes monitoring alerts and tracking file movement straightforward. Visibility into information flow between users and apps helps with audit work.
Some customers have flagged the filtering as too strict at times, with legitimate emails landing in quarantine. Users have flagged the policy customization as less flexible than expected and the advanced configuration as taking time to learn properly.
Where Harmony fits best
We think Check Point Harmony fits midmarket and enterprise teams that want one platform covering email, Teams, and file sharing rather than separate tools per channel. If your existing security stack already runs on Check Point, the integration story gets stronger.
Based on our review, expect to invest time in policy tuning during the first few months, but the cross channel visibility and detection accuracy hold up well once optimized.
Strengths
- Cross channel scanning covers email, Teams, Outlook, and shared files in one console
- ML detection catches subtle phishing that signature filters and native M365 protections miss
- API integration deploys quickly without MX record changes or mail flow rewrites
- Inbound, outbound, and internal communications all get monitored from a single unified platform
- Visibility into file and message movement helps with audit and compliance reporting work
Cautions
- Filtering can be too strict, sending legitimate emails into quarantine for users to retrieve
- Policy customization is less granular than admin teams want for varied user groups
- Initial setup and advanced configuration take time to learn and tune properly
Cloudflare Email Security
Cloudflare Email Security plugs into M365 via API and uses Cloudflare’s global threat intelligence network to catch phishing, BEC, and credential theft. It targets organizations already running on Cloudflare, or teams looking for cloud native email security that can talk to a wider SASE stack.
What makes Cloudflare’s email play different
We found the integration with the broader Cloudflare ecosystem to be the real differentiator. Browser Isolation kicks in when users click suspicious links, opening content in a sandboxed browser session, so even a successful click doesn’t put your endpoint at risk.
We saw end to end phishing triage that covers post delivery scanning and automated response workflows. SIEM and SOAR integration sit alongside, meaning email signals feed straight into your wider detection and response stack.
What customers are saying
Direct customer reviews for the Cloudflare Email Security product specifically are limited in available data. From the wider Cloudflare platform, customers say the dashboard is approachable and deployment is one of the lighter lifts in the category, with centralized control once configured.
Some customers have flagged that advanced configuration carries a learning curve. Users have flagged that several powerful features sit behind higher tier plans, which can complicate pricing decisions for smaller teams or growing businesses.
Where Cloudflare Email Security fits
We think Cloudflare Email Security makes the most sense if your organization already runs WAF, DNS, or SASE services through Cloudflare. The integration story and shared threat intelligence compound across products in ways standalone email tools can’t match.
Based on our review, teams without an existing Cloudflare footprint may find the value harder to size, but for current Cloudflare shops on M365, this is a logical extension of an existing security platform.
Strengths
- Browser Isolation opens suspicious links in a sandboxed session, protecting endpoints from successful clicks
- Post delivery scanning catches threats that slip through initial filtering and reach the inbox
- Native SIEM and SOAR integration feeds email signals directly into wider detection and response stacks
- M365 API integration deploys without MX record changes or mail flow rewrites for fast rollout
- Threat intelligence draws on Cloudflare's global network, one of the largest of its kind
Cautions
- Advanced configuration takes time to learn, particularly for teams new to Cloudflare tooling
- Several capabilities sit behind higher tier Cloudflare plans, complicating pricing for smaller teams
- Strongest value comes when paired with other Cloudflare services, less standalone value otherwise
Microsoft Defender for Office 365
Microsoft Defender for Office 365 is the native email and collaboration security layer for organizations on M365, covering Exchange Online, SharePoint, OneDrive, and Teams from a single console. It targets enterprises that want protection bundled with their productivity stack rather than added via a third party gateway.
Where Defender for Office 365 earns its place
We found the native integration to be the structural advantage here. Safe Links rewrites URLs at click time, Safe Attachments detonates suspicious files in a sandbox, and the engine runs without MX record changes or external mail flow because it sits inside the platform you already pay for.
We saw Automated Investigation and Response do useful work in higher tier plans, surfacing connected incidents and triggering remediation steps that would otherwise need analyst time. Threat Explorer adds investigative depth for SOC teams.
What customers are saying
Customers say the consolidated view across Exchange, Teams, SharePoint, and OneDrive saves real triage time, and AIR automation reduces manual remediation work for SOC teams. Threat Explorer comes up repeatedly as a strong investigation aid.
Some customers have flagged configuration as spread across too many portals, making policy management harder than it should be. Users have flagged tuning phishing and impersonation rules as time consuming, occasional false positives, and licensing tiers that take effort to explain to stakeholders.
Where Defender fits in your stack
We think Microsoft Defender for Office 365 makes the most sense if your organization already runs E5 or has the Defender Plan 2 add on. The integration depth with the rest of the Microsoft security stack is hard to replicate from outside.
Based on our review, smaller teams without E5 may find a third party tool offers better value, but for Microsoft heavy enterprises, Defender is a sensible default.
Strengths
- Native M365 integration covers Exchange, Teams, SharePoint, and OneDrive without any extra setup work
- Safe Links rewrites URLs at click time and Safe Attachments detonates files in sandbox
- AIR automates investigation and remediation workflows in higher tiers, reducing analyst manual triage time
- Threat Explorer gives SOC teams strong investigative depth across email and collaboration data sources
- Backed by Microsoft's global threat intelligence network at no extra integration cost or effort
Cautions
- Configuration spreads across multiple Microsoft portals, making policy management more confusing than necessary
- Tuning phishing and impersonation rules takes time, with false positives common during early deployment
- Advanced features sit behind E5 or Defender Plan 2 licensing, raising cost for smaller orgs
- Reporting requires multiple clicks to surface specific data during active SOC investigations
Mimecast
Mimecast Integrated Cloud Email Security is an established email security platform that integrates with M365 via API to scan inbound, outbound, and internal traffic. It targets organizations that want phishing and impersonation protection alongside archiving, electronic discovery, and compliance tooling in one place.
What Mimecast brings to the table
We found the in tenant scanning to be a real strength. The platform reaches inside the M365 tenant via API, watching not just inbound mail but outbound and internal communications, which catches lateral phishing and account takeover attempts that perimeter focused tools miss.
We saw real value in the bundled compliance tooling. Archiving, encryption, electronic discovery, and DNS filtering sit in the same console, and the Targeted Threat Protection suite handles impersonation and BEC detection that traditional filters routinely let through.
What customers are saying
Customers say the rule building interface is approachable and customization runs deep, with options to fine tune filtering by department or build custom blocks for emerging phishing patterns. Targeted Threat Protection earns repeated praise.
Some customers have flagged the admin interface as slow and deeply nested. Users have flagged inconsistent support and limited API integration with external SIEM, SOAR, and identity tools, making automation across the wider security stack harder than expected.
Where Mimecast still makes sense
We think Mimecast fits midmarket and enterprise teams that want email security paired with archiving, discovery, and compliance tooling under one vendor. For organizations needing long term mail retention, the consolidation pays off.
Based on our review, teams looking for tight integration with modern SIEM, SOAR, and identity platforms may need to weigh the API limits, but for mail protection plus compliance, Mimecast holds its ground.
Strengths
- API integration with M365 means no MX record changes or mail flow rewrites for deployment
- In tenant scanning catches inbound, outbound, and internal threats including lateral phishing attempts
- Targeted Threat Protection suite handles impersonation and BEC that signature filters routinely miss
- Bundled archiving, encryption, and discovery tools serve compliance use cases without separate vendors
- Rule customization runs deep, supporting department level filtering and custom blocks for phishing patterns
Cautions
- Admin interface runs slow and policies sit in deeply nested menus that are hard to navigate
- Limited API integration with external SIEM, SOAR, and identity tools per admin users
- Customer support quality reported as inconsistent depending on who picks up the ticket
- Advanced policy tuning can take time and feels less intuitive than newer platforms
Proofpoint Core Email Protection
Proofpoint Core Email Protection is the enterprise tier email security platform from Proofpoint, built for organizations with 500 plus users that need layered defense against phishing, BEC, ransomware, and data loss across multiple deployment models.
Where Proofpoint shows its scale
We found the threat intelligence to be the standout strength here. Nexus analyzes over three trillion emails annually, giving the detection engine a dataset most competitors can’t match, particularly on emerging campaigns and BEC patterns.
We saw real value in the deployment flexibility. You can run Proofpoint as a secure email gateway, a cloud service, or as an API integration with M365 or Google Workspace, which matters for hybrid mail environments. DMARC, DKIM, SPF enforcement, DLP, and encryption sit in the same platform.
What customers are saying
Customers say detection quality holds up over the long haul, with consistent blocking of phishing, malware, and impersonation traffic, and built in phishing simulation that saves them buying a separate awareness vendor. Daily administration runs smoothly for established teams.
Some customers have flagged false positives requiring manual release as the most consistent friction point. Users have flagged inconsistent support response times and rule synchronization issues for hybrid on premises and cloud deployments.
Where Proofpoint Core fits
We think Proofpoint Core fits large enterprises that need depth, scale, and policy control beyond what Microsoft Defender or midmarket tools provide. If you run hybrid mail or need DLP and encryption integrated, this is the tier to evaluate.
Based on our review, organizations under 500 users will find better value in Proofpoint Essentials, but for enterprise scale mail security, Proofpoint Core continues to set the bar.
Strengths
- Nexus Threat Intelligence analyzes over three trillion emails annually for detection accuracy at scale
- Flexible deployment as gateway, cloud service, or API integration suits hybrid enterprise environments
- DLP, encryption, and DMARC enforcement included in the platform without separate vendor purchases
- Phishing simulation capabilities built in, removing the need for a separate awareness training tool
- Detection quality holds up over multi year deployments according to long term admin users
Cautions
- False positives flag legitimate emails for manual release, adding admin overhead during the day
- Customer support response quality varies and sometimes runs the full SLA window per users
- Hybrid on premises and cloud deployments can have rule synchronization issues across the two portals
- Built for 500 plus user enterprises, smaller teams should look at Proofpoint Essentials instead
Proofpoint Essentials
Proofpoint Essentials is the SMB tier of Proofpoint’s email security stack, packaging URL defense, BEC protection, archiving, encryption, and DLP into one platform built for Microsoft 365. It targets small and mid sized businesses that want enterprise grade detection without enterprise grade complexity.
Why Essentials punches above its weight
We found the inline filtering deployment option to be a real shift from older Proofpoint setups. You can be up and running in under five minutes without MX record changes, which makes Essentials viable for teams that don’t have dedicated mail engineering bandwidth.
We saw real value in the bundled compliance pieces. Archiving, encryption, DLP, and Supernova BEC detection all sit in the same console, with Filter Policies replacing the regex heavy rule building that older email security tools rely on.
What customers are saying
Customers say the admin interface is straightforward to navigate, with quick user management, log searches, and quarantine release. The daily spam digest, multi domain support, and built in encryption come up as features that justify the price for smaller teams.
Some customers have flagged occasional service outages over multi year deployments and slow attachment scanning that can hold up legitimate emails. Users have flagged archiving as the weakest part of the platform, with some teams pairing Essentials with a third party archiving tool.
Where Essentials makes sense
We think Proofpoint Essentials fits SMBs and lower midmarket teams running M365 that want Proofpoint’s detection engine without enterprise pricing or operational overhead. The bundled compliance tooling is a real differentiator at this tier.
Based on our review, organizations needing serious archiving or running at 500 plus user scale should look at Proofpoint Core, but for smaller teams wanting strong all in one email security, Essentials sits well.
Strengths
- Inline filtering deployment runs in under five minutes without MX record changes for fast rollout
- URL Defense, Supernova BEC detection, and predictive URL scanning catch threats native filters miss
- Archiving, encryption, and DLP bundled in the same package without separate vendor contracts needed
- Filter Policies offer easier rule customization than regex based approaches in older email tools
- Multi domain support and daily spam digests work well for SMB and MSP environments
Cautions
- Archiving capability is the weakest part of the platform per long term admin users
- Attachment scanning can hold up legitimate emails for several minutes during peak processing times
- Service outages have occurred over multi year deployments according to some customer experiences
- Phishing simulation setup has a steeper learning curve than admins coming from other tools expect
Sublime Security
Sublime Security is a programmable email security platform built for Microsoft 365 that gives security teams full visibility into why messages get flagged. It targets organizations with technical security staff who want to write custom detections rather than rely on vendor black box filtering.
What programmable email security looks like
We found the transparency to be the real differentiator here. Every detection shows the specific signals, patterns, and behaviors that triggered it, so your team can validate threats, reduce false positives, and tune rules without guessing what the platform is doing under the hood.
We saw real value in the MQL query language and AI assisted policy builder. You can write custom detections, build automated triage workflows, and integrate alerts into Slack or email, with proactive AI threat hunting catching attacks the core ruleset missed.
What customers are saying
Customers say accuracy out of the box is high enough to skip long tuning cycles, and the engineers being the support team comes up repeatedly as a differentiator. The 700 plus built in rules give technical teams plenty of room to customize.
Some customers have flagged regional hosting inconsistencies, with new features taking time to land outside the US. Users have flagged limited bundled features like awareness training and reporting, plus a learning curve to apply actions across the rule library.
Where Sublime fits best
We think Sublime fits midmarket and enterprise teams with the technical capability to write rules and a preference for visibility over plug and play simplicity. Transparency and customization are the real draws.
Based on our review, organizations wanting awareness training and broader security tooling bundled in will need to pair Sublime with other vendors, but for teams that want programmable control, this is a strong fit.
Strengths
- Detection logic is fully transparent, showing exactly why each email was flagged or quarantined
- MQL query language enables custom detection rules and bespoke automation workflows for technical teams
- Engineers double as the support team, giving teams direct access to product expertise
- Out of the box accuracy is high enough to skip long tuning cycles during deployment
- AI assisted policy builder and proactive threat hunting cover gaps in the core ruleset
Cautions
- Regional hosting inconsistencies mean new features can take time to reach non US customers
- Doesn't bundle awareness training or broader security tooling, requiring additional vendors for full coverage
- 700 plus built in rules require trial and error to learn how to apply actions
- Some features like ADE only process data in the US, limiting fit for data residency needs
Other Email Security Services
Provides comprehensive security with AI, threat intelligence, and user behavior analysis.
Offers advanced threat protection, spam filtering, and data loss prevention for email.
Uses AI to detect and respond to advanced email threats, including insider threats.
Delivers robust email security with anti-spam, anti-malware, and sandboxing.
Enhances Office 365 security with advanced threat protection and data loss prevention.
Service Summary
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Tools / Platforms
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Price
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Link
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|---|---|---|
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TitanHQ Email Security
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$1.95 / User / Month
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IRONSCALES
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Free plan available
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Material Security
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$3.00 / User / Month
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ESET Cloud Office Security
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$121.50 / User / Year
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Microsoft Defender for Office 365
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$2.00 / User / Month
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Proofpoint Essentials
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$1.65 / User / Month
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How We Chose The Best Email Security Solutions For M365
With email remaining the number one attack vector for cybercriminals, choosing the right M365 email security platform is essential. We selected these solutions based on their proven ability to detect, prevent, and remediate advanced email threats—while maintaining seamless integration, scalability, and usability for businesses of all sizes.
Core Functionality
We focused on platforms that protect M365 users against today’s most critical threats, including phishing, Business Email Compromise (BEC), malware, and data loss. The best solutions we reviewed deliver:
- Comprehensive Threat Protection: Real-time detection of phishing, ransomware, and impersonation attacks across inbound, outbound, and internal mail.
- Seamless M365 Integration: Native API-based connections that deploy in minutes without MX record changes or mail flow disruption.
- Automated Threat Response: Post-delivery remediation tools that automatically remove malicious or suspicious emails from inboxes.
- Data Protection and Encryption: End-to-end encryption, DLP, and compliance features to secure sensitive data and meet regulatory standards.
- Visibility and Control: Centralized dashboards, policy automation, and reporting tools for effective oversight and compliance.
- Scalability: Multi-tenant support, adaptive policy management, and flexible deployment for organizations and MSPs managing large user bases.
Key Features
To ensure robust protection and smooth M365 integration, we prioritized solutions that offer:
- AI-Powered Threat Detection: Behavioral analysis, natural language processing (NLP), and anomaly detection to stop phishing and BEC attempts in real time.
- Retrospective Email Scanning: Continuous monitoring and automated remediation of threats that bypass initial filters.
- Malware and URL Defense: Advanced sandboxing, real-time URL rewriting, and malicious link scanning.
- Data Loss Prevention (DLP): Content-aware filters to prevent sensitive information from leaving the organization.
- Email Encryption: Policy-based and user-initiated encryption for regulatory compliance (e.g., GDPR, HIPAA).
- Role-Based Access Controls (RBAC): Secure, tiered access for administrators and analysts.
- User Awareness Features: Embedded training prompts, phishing simulations, and user-reporting integrations.
- Reporting and Analytics: Customizable dashboards, threat intelligence feeds, and compliance-ready reporting.
- Integration Flexibility: Support for SIEM, SOAR, and identity providers like Okta and Azure AD.
- Business Continuity: Email spooling, backup, and failover options to ensure uptime during outages.
Usability
We prioritized platforms that combine enterprise-grade protection with simplicity. Ideal solutions deploy quickly via API, integrate smoothly with M365, and minimize administrative overhead. We favored interfaces that provide clear visibility into threats, offer contextual investigation tools, and simplify configuration for IT teams and MSPs.
Scalability
Email threats evolve constantly, so scalability was key in our evaluation. The selected platforms can support rapid user growth, global operations, and complex compliance needs. They also adapt easily to hybrid and multi-cloud environments through API-based architecture and automation.
Value
We assessed each solution’s value by weighing protection strength, management efficiency, scalability, and cost. While some solutions offer lower entry pricing for SMBs, others deliver enterprise-grade capabilities with advanced analytics and multi-layered security. For accurate pricing details, contact the vendor’s sales team directly.
We independently test and analyze email security platforms to reflect how organizations protect M365 in real-world conditions. Our evaluations combine hands-on testing, vendor briefings, and user feedback to ensure each listed solution offers dependable protection and integration.
If you know of a platform that meets these criteria but isn’t included, let us know—we regularly update our listings to keep them current.
Why Trust This List
We’re an independent editorial team dedicated to helping IT and security professionals find trusted, effective solutions.
This guide was written by Craig MacAlpine, CEO and Founder of Expert Insights, who has over 20 years of experience in the email security industry. He previously founded an email security business: EPA Cloud, which was sold to J2 Global (now ZDNet) in 2013.
Our process follows a transparent, repeatable methodology to evaluate security tools on their technical merits—not marketing claims.
How we researched and verified this guide
- Hands-on testing: We conducted direct evaluations and demos of each platform, assessing phishing, BEC, malware, and ransomware detection; post-delivery remediation; M365 integration; and overall administrative usability.
- Real-world performance: We validated features like AI-driven detection, URL rewriting, attachment sandboxing, DLP, encryption, and role-based controls across both M365 and hybrid deployments.
- Market and user input: We interviewed 30+ security executives and practitioners and analyzed feedback from hundreds of organizations to understand common deployment challenges, usability preferences, and support experiences.
- Technical documentation checks: We verified each vendor’s claims against product documentation, independent test data, and peer reviews to ensure accuracy and balance.
- Pricing and deployment data: Where pricing is not publicly available, we confirmed licensing structures directly with vendors (e.g., per user/month, by feature tier, or via MSP programs).
We update this guide at least every month—and sooner when vendors release new threat protection capabilities, integrations, or pricing changes. All evaluations are conducted with full editorial independence, ensuring every recommendation is based on performance, security efficacy, and value to end users—not vendor influence.
Bottom Line
Your email security decision starts with your infrastructure and the gaps you’re trying to close.
For SMBs and MSPs running Microsoft 365 that need stronger filtering than native Defender provides without enterprise pricing, TitanHQ and Proofpoint Essentials both deliver. TitanHQ includes sandboxing as standard and suits lean IT teams managing multiple tenants. Proofpoint Essentials adds bundled archiving, DLP, and encryption for teams where compliance tooling matters alongside filtering.
Organizations where phishing and BEC are active problems and Defender isn’t catching enough should evaluate IRONSCALES and Abnormal AI. IRONSCALES deploys without MX record changes and pairs AI detection with human threat intelligence at a price point midmarket teams can justify. Abnormal AI’s behavioral baseline catches more sophisticated attacks but sits at the higher end of the category on cost, and suits enterprises that have already outgrown gateway-style filtering.
For organizations concerned about what happens after an account is compromised, not just before, Material Security is worth evaluating. Putting MFA in front of historical inbox data closes a gap most email security tools don’t attempt to address.
Teams that want cross-channel coverage across email, Teams, OneDrive, and SharePoint from a single console should look at ESET Cloud Office Security for the SMB and midmarket segment, or Check Point Harmony Email & Collaboration for larger environments with more complex policy requirements. Microsoft Defender for Office 365 makes the most sense for enterprises already running E5 or Defender Plan 2, where native integration with the broader Microsoft security stack compounds the value.
Enterprises managing long-term mail retention alongside security should evaluate Mimecast and Proofpoint Core. Mimecast bundles archiving, eDiscovery, and compliance tooling in one platform. Proofpoint Core adds deployment flexibility for hybrid mail environments and detection depth from the Nexus threat intelligence engine.
For security teams that want programmable control over detection logic rather than vendor black-box filtering, Sublime Security is the only platform in this category built around that model. Cloudflare Email Security makes the most sense for organizations already running Cloudflare WAF, DNS, or SASE services, where shared threat intelligence compounds across the stack.
The wrong email security choice generates false positives that train your users to ignore security warnings, misses the threats it was bought to stop, or adds operational overhead your team works around rather than with. The right one catches real threats quietly, integrates into the workflows your team already runs, and gives you the evidence to demonstrate program effectiveness when you need it.
FAQs
Everything You Need To Know About Email Security For Office 365 (FAQs)
Email is a very effective means of reaching to people all over the world who you may or may not know. While this is very useful, it also poses a significant risk to security. You may think that you know who you are in contact with, but how can you be sure? Some of the most common threats to your email inbox include:
- Email spoofing uses emails that appear to be legitimate, but are, in fact, fake. As these emails look legitimate, users may be tricked into giving up sensitive data, or transferring money to the attackers.
- Links or downloads attached to emails may look innocent but may actually contain malware or viruses. These are short pieces of code that can wreak havoc on your device when activated. Ransomware, for instance, will lock your important documents until you pay the attackers a ransom fee.
- Whaling is another form of email borne attack. This is a type of phishing that specifically targets high ranking executives within an organization who have power over billing and can unknowingly send money to the attackers.
Email security solutions will work in several ways to mitigate the threats facing your organization.
- Most email security solutions will be built around a filtering tool. This will use pre-set policies to block, in bulk, unwanted emails. Many solutions will also be linked to a database of known malware threats. If they identify any evidence that matches a known malware, it can quickly be deleted.
- Some email solutions will use behavioral analysis to ensure that a user is behaving in a consistent way. If a user is behaving abnormally, it might suggest that their account is compromised.
- Email security solutions may also have outbound features. These will decrease the chances of you sending sensitive information to the wrong user. Data loss prevention tools will be a part of this. Some solutions may allow you to encrypt mail before it gets sent.
Email security tools for Microsoft 365 protect email accounts, content, attachments, and users against malicious activity, compromise, or both accidental or intentional leakage. There are three commonly used approaches to implementing Office 365 email security.
First is by using Microsoft’s own internal protection: Microsoft Defender for Office 365. This is a native email security service which sits on top of the default email security included with Microsoft 365 (Exchange Online Protection). Exchange Online Protection provides advanced threat protection against zero-day malware, phishing, and business email compromises by placing warning banners on email content and automatically removing harmful email messages. This protects external recipients and results in security teams being able to empower users with advanced threat detection and swift incident response.
Second is by deploying a physical or cloud-based secure email gateway. These services monitor all incoming and outbound email traffic to remove spam and malware, using rule-based controls to prevent delivery of harmful email content. This is deployed via redirecting mail exchange (MX records) to point email towards the security service for filtering before deployment.
The third kind of email security method for Microsoft 365 is a category of “integrated cloud email security” (ICES) solutions. These cloud-native email security services deploy via API connection directly into the Microsoft 365 environment, enabling them to scan internal email content in real-time to detect compromised email accounts, phishing-threats, malicious attachments and links.
The best method of Microsoft 365 email security will depend on your specific organizational use cases and risks. SEGs are the best approach to stop malware and harmful email content, while cloud email security services can help to prevent sophisticated phishing threats that may evade the rule based controls of SEG solutions.
Written By
Craig MacAlpine is CEO and Founder of Expert Insights. Before founding Expert Insights in August 2018, Craig spent 10 years as CEO of EPA Cloud, an email security provider that rebranded as VIPRE Email Security following its acquisition by Ziff Davies, formerly J2Global (NASQAQ: ZD) in 2013.
Craig is a passionate security innovator with over 20 years of experience helping organizations to stay secure with cutting-edge information security and cybersecurity solutions.
Using his extensive experience in the email security industry, he founded Expert Insights with the singular goal of helping IT professionals and CISOs to cut through the noise and find the right cybersecurity solutions they need to protect their organizations.