10 Best Email Security Software of 2026

Defender for Office 365 earns the top spot because it gives Microsoft 365 tenants a large step up in phishing defense for very little money. Plan 1, at $2 per user per month paid yearly, adds real-time checks on links and QR codes, detonation of attachments for zero-day malware, language model based analysis aimed at phishing and BEC, and protection for internal mail. It covers Teams, SharePoint and OneDrive, which matters as attackers move into chat and shared files. Plan 2, at $5, adds threat hunting, campaign tracking, attack simulation training and automated investigation and response, plus cross-domain hunting in Defender XDR. Microsoft also publishes its own detection performance data, which helps when you compare it with third-party tools. The limits are scope and complexity: it does nothing for Google Workspace, and tuning its policies across Microsoft's admin portals takes practice. Specialist tools still catch some BEC it misses, so many teams layer one on top, but for most Microsoft 365 shops this is where to start.

Abnormal AI is the specialist pick for the attacks that worry finance and security teams most: business email compromise and vendor fraud that carry no malicious payload and pass every authentication check. Its Attune 1.0 model builds a behavioral baseline for each employee and vendor, then flags messages that depart from it, using signals such as authentication events, calendar activity and internal threads. Malicious messages and calendar invites are removed automatically, and every action shows which signals fired. Analysts get search and respond across Microsoft 365 and Google Workspace, a single quarantine view for Abnormal and Microsoft, custom AI models written in plain language, and custom rules on more than 50 message attributes. Detection 360 turns each reported miss or false positive into a tracked investigation. Because it connects by API, there is no MX change. The trade-off is cost visibility: Abnormal publishes no prices, and its depth is aimed at organizations with a security team rather than a single IT generalist.

Material Security takes a wider view than most email tools: it treats the mailbox as part of the cloud workspace and protects the accounts and files around it. Essentials, at $4 per user per month billed annually plus a fee tied to Shared Drive size, includes automated detection and response for phishing, BEC, impersonation and fraud, an agent that processes user-reported phish, email bomb detection, threat hunting with custom detections, and training touches such as speedbumps and simulations. It also inventories connected OAuth apps and flags posture problems such as MFA gaps, inactive accounts and mail forwarding. Advanced, at $6, adds sensitive content detection in Shared Drives and email and agentic OAuth remediation. The ATO Resilience add-on, $3 more, puts message-level MFA in front of sensitive and password reset emails so a stolen login does less damage. The drawbacks are the separate Shared Drive fee and that some mailbox types need a quote. For Google Workspace shops in particular, it is one of the few tools that covers email and account risk at a published price.

Check Point's email product stands out for blocking threats before delivery while still connecting by API. Most API tools pull bad mail out after it lands, but Check Point inspects each message first and can run in monitor mode during evaluation, then move to inline prevention without touching MX records. Detection runs through ThreatCloud AI, which Check Point says combines more than 50 AI engines with behavioral, identity and language analysis and global threat intelligence. Coverage reaches beyond Microsoft 365 and Google Workspace mail to Teams, SharePoint, OneDrive and Slack. It also screens for malicious prompts and hidden instructions aimed at AI assistants such as Copilot and Gemini that read email. The Complete package layers on DLP, DMARC, security awareness training, account takeover protection and archiving. Pricing is quote only and the package matrix takes some reading, but for teams that want one tool across mail and chat with prevention before the inbox, it is a strong fit.

Ironscales is built for teams that cannot staff a full email security desk. It connects to Microsoft 365 or Google Workspace by API, so there is no MX change or gateway, and its agentic AI removes phishing, spam and graymail on its own. Email Essentials already includes detection for phishing, BEC and VIP impersonation, dynamic warning banners inside messages, a Report Phishing add-in for Outlook, crowdsourced threat intelligence and URL scanning. Email Protect adds multi-engine scanning of links and attachments, advanced spam handling and control over how far remediation runs on its own. Email Protect 360 adds encryption and data loss prevention for outbound mail. Domain lookalike detection and protection against QR code and image-based phishing round out the detection set. Ironscales also runs a partner program for MSPs. The catch is that no tier has a public price, and attachment sandboxing is not in the entry plan, so compare tiers carefully before you request a quote.

MailRoute is a straightforward filtering service that sits in front of your mail server and publishes its price list in full. Basics costs $2 per user per month and includes inbound and outbound security, content filtering, DKIM signing, quarantine notifications, real-time mail logs and integration with Microsoft 365 and Google Workspace. Impersonation protection is available on all plans in early access. Enterprise, at $3, adds phone support, SSO, LDAP and Active Directory sync, an API, white-glove onboarding and an always-on 30-day email continuity store users can reach during outages. Enterprise U.S., at $4, keeps data in US datacenters with US-citizen-only access, and supports ITAR, HIPAA with a BAA and NIST 800-171. Every tier queues mail for up to 15 days if your server stops responding. Aliases and distribution lists cost nothing, and there are no seat minimums or contracts. What it lacks is behavioral detection of BEC and post-delivery removal, so treat it as a dependable filter and outage buffer rather than a full anti-BEC platform.

Phish Protection, run by DuoCircle, is one of the few email security services that shows its full price on the website and lets you buy without a sales call. The base fee is $32 per month and covers 10 users, then each additional mailbox costs $1.80 per month, falling to $1.60 at larger volumes, and shared mailboxes cost half. Every plan includes the same features: real-time protection, advanced threat defense with AI-powered URL analysis, time-of-click link checks, attachment sandboxing, display name spoofing detection, blocklists and allowlists, and a reporting dashboard. It works with Microsoft 365, Google Workspace and any mail system that supports standard routing, and support is 24/7 and US based. There is a 60-day free trial with no credit card and no long-term contract. The trade-off is depth: it is a filtering layer rather than an API tool that learns each user's normal behavior, so it is weaker against carefully written BEC with no link or file. For a small office that wants solid phishing filtering on a known budget, it is easy to recommend.

Proofpoint is the heavyweight option for large organizations that want one vendor across every stage of email delivery. Core Email Protection can run as a secure email gateway, through an API connection to Microsoft 365 via Microsoft Graph, or both, which gives inline, in-mailbox, post-delivery and click-time coverage. Detection uses multi-model behavioral AI trained on Proofpoint's view of threat campaigns, and the Threat Protection Workbench brings inbound, internal, account and supplier compromise into one investigation view. Users see dynamic warning banners on suspicious mail, and the Satori Abuse Mailbox Agent automates the triage of reported messages. Proofpoint also adds domain fraud detection and takedown and outbound data controls, which few rivals bundle. Detections can appear inside the Microsoft 365 console for analysts who live there. The costs are price opacity and operational weight: there is no published price, and the range of modules takes skilled staff to tune. For a global enterprise with gateway requirements, it remains one of the most complete choices, but smaller teams will find simpler tools easier to run.

Mimecast suits organizations whose mail is not purely in the cloud. It protects Microsoft 365, Google Workspace and on-premises or hybrid environments, and you can deploy it as an MX-based gateway that blocks bad mail in line or without a gateway. Detection combines anomaly detection based on social graphing, sandboxing to catch evasive files, on-click link protection and computer vision that spots brand and login page impersonation. Contextual banners warn users in the message and support remediation of threats such as QR code phishing and BEC. The platform connects to SIEM and XDR tools for shared threat intelligence, and adds Mimecast's own Continuity, DMARC, security awareness training and Archiving modules, so one vendor can cover filtering, outage access and retention. Mimecast says 42,000 customers use it. The downsides are a quote-only model, more setup for gateway deployments and a larger set of modules to manage. If your estate is hybrid or you want archiving and continuity with your filter, it is a sound choice; cloud-only teams can get faster results from API tools.

Paubox is a specialist for healthcare, where email security has to cover HIPAA as well as phishing. Its Plus plan, the entry point for inbound protection, costs $65 per month billed annually for up to five senders. Plus filters inbound mail for spam, ransomware and phishing, adds malware and virus scanning, and uses ExecProtect+ to stop display name spoofing of practice leaders. It keeps the core of every Paubox plan: outbound email is encrypted automatically and recipients read it without a portal or password, which patients appreciate. Paubox works with Google Workspace and Microsoft 365, includes a business associate agreement, is HITRUST certified and offers US-based support. Premium, at $75, adds archiving and data loss prevention. The limits are scope and scale: it is not built for behavioral BEC detection in large organizations, and sender-based pricing climbs as headcount grows. For a clinic or a health tech vendor that needs compliant encryption and decent inbound filtering from one provider, it fits well.