Best Email Security Solutions in 2026

Proofpoint was founded in 2002 by Eric Hahn, a former chief technology officer of Netscape, and is headquartered in Sunnyvale, California; private-equity firm Thoma Bravo acquired it in 2021. The company cites more than 5,000 employees, more than two million customers worldwide and more than half of the Fortune 100 as customers. Core Email Protection can run as a secure email gateway (SEG), inspecting mail inline before it enters or leaves the organisation, or through APIs connected directly to Microsoft 365 without MX record changes, and covers inline, in-mailbox, post-delivery and click-time protection. Threat Protection Workbench brings inbound, internal, account and supplier threats into a single investigation view, and the Satori Abuse Mailbox Agent handles user-reported messages. In December 2025 Proofpoint completed the US$1.8 billion acquisition of Hornetsecurity, adding an MSP-focused Microsoft 365 product for smaller organisations. Detection claims on the product page, such as blocking 99.999% of advanced threats, are vendor statements without published methodology. Prices are not published, and the breadth of the portfolio can make packaging hard to compare.

Microsoft Defender for Office 365 is the security layer built into Microsoft's email and collaboration services, and is the baseline against which most third-party email security tools are evaluated. Plan 1 costs US$2.00 per user per month and includes real-time protection against malicious links and QR codes and protection against zero-day malware in attachments; Plan 2 costs US$5.00 per user per month and adds cyberattack simulation training and automated investigation and response. Both plans are billed annually and offer a one-month free trial that requires a credit card. Enterprises on Microsoft 365 E3 can instead buy the Microsoft Defender Suite at US$12.00 per user per month, which combines email protection with endpoint, identity and SaaS security. The product's advantages are price, absence of mail-routing changes and native correlation with other Microsoft Defender products. Its limitation is that it only protects Microsoft's own mail platform, and many organisations layer an API-based specialist such as Abnormal or a gateway such as Proofpoint or Mimecast on top for behavioural detection of business email compromise.

Mimecast was founded in 2003 and is headquartered in London; it says it serves more than 42,000 organisations and 27 million users in more than 100 countries. Its Advanced Email Security product can be deployed in two ways. In MX-based deployment all incoming mail routes through Mimecast's gateway, which intercepts threats inline and can keep mail flowing if the primary mail server is down; in API-based deployment Mimecast connects to the cloud mail platform without MX changes or disruption to mail flow. Detection uses anomaly detection with social graphing, advanced sandboxing, on-click protection and computer vision to identify brand and login-page impersonation, and contextual banners warn users about QR-code phishing and business email compromise. Mimecast supports Microsoft 365, Google, on-premises and hybrid environments, and integrates with SIEM and XDR platforms and named partners such as CrowdStrike, Netskope and Palo Alto Networks XSOAR. It cites Leader placement in Gartner's 2025 Magic Quadrant for Email Security. Prices are quote-based, and the continuity feature that distinguishes the gateway option is not available in API-only mode.

Abnormal was founded in 2018 by Evan Reiser and colleagues from the advertising-technology industry, and says more than 30% of the Fortune 500 use it. Its platform page cites 5,000 organisations as customers. Abnormal takes an API-based, behavioural approach to email security: rather than sitting in the mail flow, it connects to Microsoft 365 or Google Workspace through APIs, which the company says takes 60 seconds and requires no MX changes, and learns normal communication patterns in order to flag deviations. Its Behavior Engine and the Attune 1.0 model are trained on behavioural signals rather than signatures. Email products include Inbound Email Security, an AI Security Mailbox for user-reported messages, AI Phishing Coach, email productivity filtering, misdirected email and DLP rules; identity products include account takeover protection; and the company now also sells AI security modules for governing AI agents and employee AI use. The platform lists more than 100 native API integrations. Limitations: there is no pre-delivery gateway, so some messages reach the mailbox before removal, and pricing is not published.

Harmony Email & Collaboration is Check Point's cloud email and collaboration security product. It deploys through APIs in minutes without changing MX records, and enforcement can range from monitor mode to inline prevention. Coverage extends beyond Microsoft 365 and Google Workspace mail to Microsoft Teams, Slack and file-sharing services such as Dropbox, Box and ShareFile, and the page says it also protects AI assistants such as Microsoft Copilot and Google Gemini from malicious prompts hidden in email. The suite bundles data loss prevention, DMARC authentication, security awareness training, account takeover protection and email archiving. Check Point states that the product protects more than 80,000 organisations, draws on more than 50 AI engines in ThreatCloud AI, and was named a Leader in Gartner's 2025 Magic Quadrant for Email Security; vendor-stated prevention rates of 99.9% for malware and 99.7% for phishing are given without methodology. Packages are selected on a separate page and prices are not shown.

Darktrace says it has been building its approach to cybersecurity since 2013, lists offices in Cambridge, New York, London and Singapore, and cites 10,000 customers and more than 2,300 employees. Darktrace / EMAIL differs from most rivals in training on each organisation's own activity and users rather than on a shared cross-customer model, which the company argues catches targeted attacks that signature and crowd-sourced models miss. Components are Adaptive Email Security against phishing, business email compromise and AI-generated attacks; Identity Detect & Respond for account takeover; email DLP with detection and alerting across Teams, Zoom and Slack; and adaptive security awareness training in which per-user risk scores adjust email controls. Darktrace cites Leader placement in Gartner's 2025 Magic Quadrant for Email Security. The product page does not describe the deployment model or prices, and some statistics on it are attributed inconsistently, so buyers should request the evidence behind any figures they rely on.

Cisco Secure Email combines inline gateway filtering and API-based post-delivery remediation in a single console. Its Threat Defense component stops threats before they reach the mailbox, adds relationship-graph context to content analysis, and uses AI to assess the intent and risk of a message. The product page states that it is FedRAMP Class D (High) certified, which matters for US federal agencies and contractors. Secure Email Threat Defense is priced per user on one-, three- or five-year subscriptions with discounts for multi-year terms, and can be billed monthly, quarterly, annually or upfront without a surcharge; subscriptions include 24/7 Cisco TAC support and customer-success onboarding, and can be bought through Security Bundles, Enterprise Agreements or Cisco Capital financing. Gateway licences are described on a separate page. The page does not list dollar amounts or tiers, and does not say how Cisco's threat-intelligence group feeds the product, so buyers comparing detection depth will need technical documentation.

Barracuda Networks sells Email Protection as a suite that combines threat protection with adjacent functions most rivals sell separately. The product page lists domain fraud protection (DMARC), incident response, and integrated backup for Microsoft 365 data among its use cases. A free email threat scan, which Barracuda says takes less than five minutes and needs no MX changes, reports personalised attacks, post-delivery threats and account-takeover signals already present in a tenant, and a free trial is available. The company says hundreds of thousands of IT professionals and managed service providers use its products, and its copyright line dates back to 2003. Barracuda's appeal is consolidation: small IT teams can cover filtering, incident response, DMARC reporting and backup with one contract. The product page itself gives little technical detail and no plan names or prices, which are on a separate plans page, so detailed comparison requires a sales conversation.

Hornetsecurity sells 365 Total Protection, an all-in-one suite covering security, backup, compliance and awareness training for Microsoft 365. Its premium services are used by more than 125,000 customers through more than 12,000 channel partners and MSPs. Proofpoint completed its acquisition of Hornetsecurity on 8 December 2025 for total consideration of US$1.8 billion; at that time Hornetsecurity generated annual recurring revenue of nearly US$200 million, growing 20% a year, and operated in more than 120 countries. Proofpoint described the deal as extending its reach to small businesses and MSPs and reinforcing its commitment to Europe, and the site is now branded "Hornetsecurity by Proofpoint". The email-security technology of Vade, a company co-founded by Hornetsecurity's chief product officer, now forms part of Hornetsecurity. The suite suits MSPs that want to bundle filtering, backup and training per tenant. The about page does not state a founding year or headquarters, and prices are set by partners.

Sophos Email uses multi-layered AI and machine-learning models, including natural-language processing, to detect phishing, business email compromise and impersonation, with SPF, DKIM and DMARC checks and anti-spoofing enforcement. Attachments are sandboxed, URLs are rewritten for time-of-click checks, malicious links hidden in QR codes or images are detected, and messages flagged after delivery are removed. DLP policies can encrypt sensitive email automatically, with Portal Encryption for secure sharing, and phishing simulation and training come through Sophos Phish Threat. Deployment can be API-based for Microsoft 365 and Google Workspace, without MX changes, or as a gateway that filters mail before delivery. Management is in Sophos Central (Fusion), and Synchronized Security shares telemetry between mailbox and endpoint, while Sophos MDR and XDR can investigate email-borne incidents. DMARC Manager and an Email Monitoring System are add-ons. Prices are not published; trials are available from the console for existing customers or by form.

IRONSCALES sells API-based email security for Microsoft 365 and Google Workspace in five tiers. Email Essentials covers AI-based phishing, BEC and VIP impersonation detection, agentic autonomous remediation, basic spam and graymail filtering and URL scanning; Email Protect adds advanced spam, URL and attachment scanning with customisable remediation; Email Protect 360 adds encryption and email DLP; Email Protect Pro adds centralised threat analysis, account takeover protection and an Email Incident Management Service for MSP analysts; and Complete Protect adds account takeover protection, integrated security awareness training and unlimited phishing simulation. A separate Human Risk Management tier provides simulation and training without email security. A free trial and a free email health scan are offered, but all tiers require a quote, and the pricing page contains a duplicated tier label that buyers should clarify.

FortiMail is the only product in this list offered in every deployment form: five hardware appliance models, six virtual appliances sized by CPU and domain, FortiMail Cloud Hosted in Fortinet's data centres, and FortiMail Cloud SaaS for Microsoft 365 and Google Workspace, with gateway and Graph API support models for cloud mail. Fortinet says the appliances filter from 40,000 to 2.6 million messages per hour, based on FortiOS 7.0 with antispam and virus-outbreak services enabled, and cites a June 2024 Virus Bulletin VBSpam review reporting a 99.96% spam catch rate and 99.84% malware detection. Licensing differs by form: appliances and VMs use perpetual licences with annual subscriptions (VMs also have a full subscription option), the hosted service is priced per mailbox per year and the SaaS per user per year. Fortinet was named a Challenger in Gartner's 2025 Magic Quadrant for Email Security. FortiMail suits organisations that run their own mail servers or must keep mail processing on premises. No dollar prices are published.

Material Security protects Google Workspace and Microsoft 365 through APIs, treating email as one part of a broader cloud-workspace security problem. Its inbound email security targets phishing, social engineering and business email compromise. Beyond the inbox, an OAuth Remediation Agent shows what authorised third-party apps and AI agents do with their access and lets administrators revoke it; a Drive Agent finds over-shared sensitive files and remediates them in bulk; and account-takeover containment redacts sensitive historical messages and applies message-level access controls so that stolen credentials expose less data. Posture management covers tenant configuration. Customers named on the home page include Mars, Lyft, Figma, Reddit, OpenAI, Anthropic, Datadog and PagerDuty. Material's distinctive idea is limiting the damage of a compromised mailbox rather than only filtering inbound mail. Its home page gives no founding details or prices, and the product is newer and less widely deployed outside technology companies than the gateway vendors in this list.