The best email security software in 2026 is Proofpoint for enterprise email protection, Abnormal AI for AI driven behavioural defence, Mimecast for all round email security and resilience, Microsoft Defender for Office 365 for Microsoft 365, and Barracuda for value and SMBs. Below we compare the 19 leading email security platforms on price, features, ratings and who each one suits best.
Sponsored placement on this category page.
Ranked on verified ratings, pricing, feature depth and fit.
A leading enterprise email security platform with strong threat protection, threat intelligence, DLP and people centric defence, the long standing choice for large organisations protecting email.
An AI native email security platform that models normal behaviour to stop advanced attacks like BEC and account takeover, API integrated with Microsoft 365 and Google, highly rated and fast growing.
An all round email security and resilience platform with threat protection, archiving and continuity, a long established choice for organisations wanting security plus email resilience and compliance.
An email protection platform strong on value and ease, with threat protection, anti phishing and backup, popular with SMBs and mid market wanting capable email security without enterprise complexity.
Cisco's email security with strong threat defence and integration with the Cisco security portfolio, suited to organisations in the Cisco ecosystem wanting integrated email protection.
Microsoft's email security for Office 365, with threat protection built into Microsoft 365 and often included in E5, the natural choice for organisations protecting Microsoft 365 email.
Check Point's API based email security (Harmony Email) that catches phishing and advanced threats inside Microsoft 365 and Google, suited to teams wanting API deployed, AI driven protection.
An AI driven anti phishing platform combining automated detection, remediation and user training, API integrated, popular with mid market teams focused on stopping phishing and BEC.
Trend Micro's email security within its broad security suite, with threat protection and cloud email defence, suited to organisations wanting email security from a major security vendor.
A cloud email security and backup suite focused on Microsoft 365, popular with SMBs and MSPs for protection, archiving and backup, with strong value and partner focus.
| Tool | Rating | Starts at | Free plan | Best for |
|---|---|---|---|---|
| Proofpoint | ★ 4.4 | Per user quote | No | Enterprise email protection |
| Abnormal AI | ★ 4.8 | Per user quote | No | AI driven behavioural defence |
| Mimecast | ★ 4.4 | Per user quote | No | All round security and resilience |
| Barracuda | ★ 4.5 | Per user quote | No | Value and SMBs |
| Cisco Secure Email | ★ 4.4 | Per user quote | No | Cisco ecosystem email security |
| Microsoft Defender for Office 365 | ★ 4.5 | From ~$2/user/mo; in M365 E5 | No | Microsoft 365 protection |
| Check Point Harmony Email | ★ 4.5 | Per user quote | No | API email security |
| IRONSCALES | ★ 4.6 | Per user quote | Yes | AI phishing defence |
| Trend Micro | ★ 4.5 | Per user quote | No | Broad security vendor email |
| Hornetsecurity | ★ 4.6 | Per user quote | No | Microsoft 365 security for SMB/MSP |
Market size and forecast · 8.41% CAGR. Sources: Market Research Future, G2, Capterra
The figures that define the email security market, each linked to its original source so you can verify every number.
| Metric | Figure | Source |
|---|---|---|
| Email security market, 2025 | $7.39B | marketresearchfuture.com |
| Forecast CAGR to 2035 | 8.41% | marketresearchfuture.com |
| Projected market, 2035 | $16.57B | marketresearchfuture.com |
| Growth drivers | Phishing + AI | marketresearchfuture.com |
| Core job | Protect email from threats | Market Research Future |
| Who uses it | Security and IT teams | Market Research Future |
| Why it matters | Email is the top attack vector | Market Research Future |
| Tools compared | 19 | 6S Software directory |
Email security software protects email, the top attack vector, from threats like phishing, business email compromise (BEC), malware, ransomware, spam and data loss. It filters inbound email to block malicious messages, detects and stops phishing and impersonation, scans attachments and links (often sandboxing them), protects against spoofing with authentication (SPF, DKIM, DMARC), and increasingly uses AI to spot advanced, socially engineered attacks. Many platforms add outbound protection and data loss prevention (DLP), encryption, user awareness training, and email continuity and archiving. Modern tools deploy either as a gateway in front of email or via API inside cloud email (Microsoft 365, Google Workspace). Used by security and IT teams, email security defends the channel attackers use most. The goal is to stop email borne threats and protect data, while keeping legitimate email flowing.
It matters because email is the number one way attackers get in, through phishing, BEC and malware, and native email filtering alone often misses advanced, targeted attacks, so dedicated email security adds stronger, AI driven protection against the threats that cause most breaches and fraud. As attacks grow more sophisticated and AI driven on both sides, demand expands. The email security market reached about 7.39 billion US dollars in 2025 and is forecast to reach 16.57 billion by 2035, an 8.41 percent compound annual growth rate [Market Research Future].
Email security inspects messages for threats. Traditional secure email gateways (SEGs) sit in front of email, filtering all inbound (and often outbound) messages before delivery, blocking spam, malware and phishing, scanning and sandboxing attachments and links, and enforcing authentication (SPF, DKIM, DMARC) against spoofing. Modern, API based tools instead connect directly to cloud email (Microsoft 365, Google Workspace) via API, analysing messages inside the mailbox, which lets them use context and behaviour and catch threats that pass the gateway. AI and behavioural analysis increasingly model normal communication patterns to detect BEC, impersonation and account takeover that signature based filtering misses. Platforms also add DLP and encryption for outbound data, user awareness training and phishing simulations, and some add continuity and archiving.
The category spans enterprise gateways, AI native and API tools, Microsoft and vendor suites, and value and SMB focused options. Enterprise platforms like Proofpoint, Mimecast and Cisco Secure Email offer comprehensive protection, often as gateways, with threat intelligence, DLP and more. AI native and API based tools like Abnormal AI, Check Point Harmony Email, IRONSCALES, Sublime Security and Material Security analyse email via API and use behaviour and AI to stop advanced attacks. Microsoft Defender for Office 365 protects Microsoft 365 natively. Broad security vendors like Trend Micro, Fortinet, Sophos and Barracuda include email security in their suites, with Barracuda and Hornetsecurity strong for SMBs and MSPs. The right tool depends on your email platform, threat focus, gateway versus API, and size.
Email security tools vary in approach and depth, so match to your needs.
Enterprise platforms include Proofpoint, Mimecast and Cisco Secure Email. AI native and API tools include Abnormal AI, Check Point Harmony Email and IRONSCALES. Microsoft protects Microsoft 365 with Defender for Office 365. Value and SMB focused options include Barracuda and Hornetsecurity.
Start with your email platform and threat focus. For comprehensive enterprise protection, Proofpoint leads, with Mimecast for security plus resilience and archiving, and Cisco Secure Email in the Cisco ecosystem. For AI driven defence against advanced attacks (BEC, account takeover) via API, Abnormal AI, Check Point Harmony Email or IRONSCALES. For Microsoft 365, Microsoft Defender for Office 365 (often in E5), though many add a third party layer. For value and SMBs, Barracuda or Hornetsecurity. Match the tool to your email platform (Microsoft 365, Google), gateway versus API deployment, threat and compliance focus, and size.
Then weigh three practical factors. First, deployment model, API based tools (Abnormal, Harmony, IRONSCALES) deploy fast inside cloud email and catch threats using context, while gateways (Proofpoint, Mimecast) sit in front and offer comprehensive control, and many organisations layer an API tool on top of Microsoft 365. Second, threat focus and AI, advanced phishing and BEC need behavioural, AI driven detection, not just signatures. Third, extras and ecosystem, consider DLP, encryption, user training, continuity and archiving, and fit with your email platform and security stack, plus pricing, usually per user per month. Trial with your real mail flow, and cross check verified reviews on G2 and Capterra.
Email security is almost always priced per user per month (or per mailbox), and most vendors quote for business. Microsoft Defender for Office 365 is around 2 US dollars per user for Plan 1 and 5 for Plan 2, and Plan 2 is included in Microsoft 365 E5, so many Microsoft organisations have it. Third party platforms, Proofpoint, Mimecast, Abnormal, Barracuda and others, are typically a few dollars per user a month and quoted, varying by features (threat protection, DLP, training, archiving, continuity). Bundled suites and SMB and MSP focused tools (Barracuda, Hornetsecurity) can be cost effective, and comprehensive enterprise platforms cost more.
The main cost drivers are the number of users and the capabilities you need, basic threat protection versus added DLP, encryption, user training, continuity and archiving. For Microsoft organisations, Defender for Office 365 may add little cost if in E5, though many still layer a third party tool for stronger advanced threat and BEC protection, which is an added per user cost worth weighing against risk. API based tools are often quick to deploy and priced per user. Decide whether the native protection suffices or you need an added layer, and which extras matter. Model total cost by users and features, and use trials, which run on your real mail, to evaluate detection before committing.
AI is the defining battleground, with attackers using AI to craft convincing phishing and BEC, and defenders using AI and behavioural analysis to detect them, driving the rise of AI native platforms like Abnormal. API based deployment inside Microsoft 365 and Google continues to grow over traditional gateways, for faster deployment and context aware detection, often layered on native protection. BEC, impersonation and account takeover remain the costliest threats, pushing behavioural defence. Integration with the wider security stack (SIEM, XDR) and automated remediation are increasing, and user awareness training is often bundled as the human layer of defence.
Native placement between content sections.