Best 12 Email Security Solutions For Microsoft 365 (2026)

• Multi-layered inbound threat protection with spam filtering, attachment sandboxing, and real-time URL scanning.
• Scans all inbound emails in real time, filtering out malicious content including phishing links and malicious attachments.
• Outbound data leak prevention rules prevent email data loss.
• Granular policy configuration by user, domain, and domain group with straightforward allow/deny lists.
• Easy integration with Microsoft 365 with enhanced threat protection and reporting.

We think SpamTitan is an easy-to-manage email security solution for SMBs, enterprises, MSPs, and resellers that need comprehensive inbound threat protection without a complex deployment. The 99.99% catch rate and included sandboxing are strong value, and the outbound DLP capabilities add a layer of protection that many competing gateways lack. SpamTitan is also a strong option for education environments, where its cost-effective pricing model keeps it accessible.

• Connects to Microsoft 365 via Graph API with no MX record changes, mail flow rules, or connector configuration.
• Behavioral baselines flag suspicious email activity in real time with one-click Outlook reporting fed into 17,000+ customer organizations.
• Themis virtual SOC conducts autonomous investigation and remediation with admin context on email threats.
• Machine learning, AV engines, and URL scanning with standalone spam and grey-mail filtering.
• Deepfake meeting protection for Microsoft Teams video calls.
• Predictive red team agent generates attack scenarios from your organization’s public footprint.

We are impressed by IRONSCALES. The platform is constantly adding new features, like email spam filtering, encryption, and deepfake protection. The core of the product is the crowdsourced threat intelligence built on end-user email reporting, which is an effective way of blocking phishing, alongside powerful threat protection engines. If you are running Microsoft 365 and looking for a dedicated mailbox-layer tool for phishing and account compromise detection, IRONSCALES delivers. The free Starter tier offers phishing simulation and testing for up to 500 mailboxes, though full email protection requires a paid plan.

• Scans historical mail for sensitive content like tax records and invoices, then locks it behind MFA.
• Emails automatically classified as sensitive are hidden in the inbox until the user re-authenticates, limiting what a compromised account can exfiltrate.
• API deployment runs in under 30 minutes with no MX record changes required.
• Account takeover detection covers 2FA scams, password resets, and configuration drift.

Customers say the automatic clustering of similar phishing messages saves investigation time, and the ‘report suspicious message’ button is one of the simpler features to roll out to end users. Based on customer feedback, the account takeover detection, which covers 2FA scams, password resets, and configuration drift, is a standout capability.

We were impressed by the approach to protecting stored inbox data, which closes a gap most email security tools don’t attempt to address. If your concern is what happens after an account is compromised rather than just blocking initial delivery, Material Security deserves a look.

• Same ESET antimalware engine applies consistently across email, files, and collaboration tools.
• Policy flexibility at user, group, or organization level suits MSPs managing varied client environments.
• Native M365 integration deploys without MX record changes or mail flow rewrites.
• Clean dashboard makes daily management manageable for smaller IT teams.

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 low once the platform is tuned.

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 is low once the platform is tuned.

• Analyzes communications against more than 45,000 threat indicators, learning normal patterns for each user.
• 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.
• Graymail filtering and accurate detection reduce time SOC teams spend on email triage.

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. Graymail filtering and accurate detection reduce the time SOC teams spend on email triage.

We were impressed by the auto-remediation, which forces logouts and resets credentials when accounts show signs of compromise. If your M365 environment has outgrown gateway filtering and you need a behavioral layer that catches what your SEG misses, Abnormal AI is a strong candidate.

• Sits within the M365 environment to secure inbound, outbound, and internal emails, catching threats perimeter gateways miss.
• Machine learning models analyze over 300 indicators of compromise including sending time, location, and domain patterns.
• URL protection, sandboxing, DLP, and account takeover prevention across email, Outlook, Teams, and shared files from a single console.
• ML detection catches subtle phishing attempts that signature filters and native M365 protections miss.

Customers say threat detection runs quietly without slowing daily work, and the dashboard makes monitoring alerts and tracking file movement straightforward. Some users report the filtering can be too aggressive at times, sending legitimate emails into quarantine.

We think Check Point Email Security fits midmarket and enterprise teams that want one platform covering email, Teams, and file sharing rather than separate tools per channel. Deployment as an app within the Microsoft 365 environment keeps the setup process manageable, and the cross-channel coverage is a genuine differentiator for organizations running collaboration tools beyond just email.

• ML models analyze email content, intent, tone, sender relationships, and other attack signals.
• Post-delivery scanning catches threats that slip through initial filtering.
• Browser Isolation opens suspicious links in a sandboxed session, protecting endpoints from successful clicks.
• Native SIEM and SOAR integration feeds email signals directly into wider detection stacks.

Direct customer reviews for Cloudflare Email Security specifically are limited. From the wider Cloudflare platform, customers say the dashboard is approachable and deployment is one of the lighter lifts in the category.

We think Cloudflare Email Security makes the most sense if your organization already runs WAF, DNS, or SASE services through Cloudflare. If you’re evaluating email security as a standalone purchase without existing Cloudflare investment, other vendors on this list offer more out-of-the-box depth.

• Safe Links rewrites URLs at click time and Safe Attachments detonates suspicious files in a sandbox before delivery.
• Anti-phishing protection uses machine learning and impersonation detection to block targeted attacks.
• Automated Investigation and Response (Plan 2) surfaces connected incidents and triggers remediation automatically.
• Extends protection to SharePoint, OneDrive, and Teams natively, which few third-party tools cover.

Customers say AIR automation reduces manual remediation work for SOC teams, and Threat Explorer comes up repeatedly as a strong investigation aid. Some users report that configuration is spread across multiple Microsoft portals, making policy management more complex than expected.

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 difficult to replicate with third-party tools. For organizations that rely heavily on Defender, adding a third-party layer like IRONSCALES or Abnormal AI on top is a common approach to address the gaps in advanced phishing detection.

• Deploys as MX-based gateway or via API for in-tenant scanning, with flexibility in how email traffic is routed and inspected.
• Internal Email Protect detects and remediates internal threats alongside Security Awareness Training.
• Mailbox-level compliant archiving provides e-discovery, legal hold, and M365 continuity during outages.
• Email encryption, DNS filtering, and 350+ vendor integrations (March 2026 update) bundled in the platform.
• Deep rule customization supports department-level filtering and custom phishing blocks.

Customers say the rule-building interface is approachable, with options to fine-tune filtering by department or build custom blocks for emerging phishing patterns. Targeted Threat Protection earns repeated praise from enterprise admin teams for its accuracy on targeted attack campaigns.

We think Mimecast works well for organizations that need email security and compliance tooling from a single vendor. The combination of MX gateway and in-tenant scanning, archiving, encryption, DNS filtering, and Security Awareness Training means Mimecast can serve as a complete Microsoft 365 email security solution without requiring multiple separate purchases. The March 2026 update adds 350+ vendor integrations, addressing the main connectivity criticism.

• Nexus threat intelligence feeds the detection engine with data from over three trillion emails annually.
• Deploys as MX-based gateway, cloud service, or API integration alongside existing mail routing.
• DLP, encryption, and DMARC enforcement included without separate vendor purchases.
• Built-in phishing simulation saves separate awareness training platform purchases.

Customers say detection quality holds up over the long haul, with consistent blocking of phishing, malware, and impersonation traffic. Built-in phishing simulation saves them buying a separate awareness training platform.

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 in the same platform, this is one of the few vendors that handles the full stack without requiring separate purchases.

• Multi-layered detection engine covers spam, malware, phishing, and BEC.
• URL Defense blocks malicious links at time of click and Supernova BEC detection catches threats native M365 filters miss.
• Inline filtering deployment gets up and running in under five minutes without MX record changes.
• Archiving, encryption, and DLP bundled without separate vendor contracts with multi-domain support.

Customers say the admin interface is straightforward, with quick user management, log searches, and quarantine release. The daily spam digest, multi-domain support, and built-in encryption come up as practical features that save time for lean IT teams.

We think Proofpoint 365 Total Protection fits SMBs and lower midmarket teams running M365 that want Proofpoint’s detection engine without enterprise pricing. The bundled compliance tooling is a real differentiator at this price point. SE Labs testing has rated Proofpoint among the highest for email threat detection accuracy across market-leading vendors.

• MQL query language lets you write custom detections, build automated triage workflows, and integrate alerts into Slack or email.
• EML Analyzer provides a VS Code-like interface for inspecting messages, testing rules, and building new detection logic.
• Out-of-the-box accuracy high enough to skip long tuning cycles during deployment.
• Engineers who built the product double as the support team for direct access to product expertise.

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. According to customer feedback, regional hosting inconsistencies mean new features take time to reach non-US customers.

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. If your security team wants programmable detection and direct access to the people who built the platform, Sublime is worth evaluating.