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Best Cloud Email Security Alternatives to Proofpoint in 2026

Cloud email security platforms provide email threat protection delivered entirely as SaaS, without requiring on-premises appliances or infrastructure.

3 Cloud Email Security Platforms, side by side

ToolDeploymentPricing modelOpen source
Microsoft Defender for Office 365CloudPer-user subscription (bundled with Microsoft 365 E5)—
Trend Micro Email SecurityCloudPer-user subscription—
MimecastCloudPer-user subscription—

These platforms integrate natively with cloud email services like Microsoft 365 and Google Workspace, either through inline gateway deployment or API-based connectivity. Cloud email security is the fastest-growing segment of the email security market as organizations move to cloud-native architectures and want security solutions that match their deployment model.

By use case

Our read on which tool suits which job. Editorial, not paid, and separate from the listing below.

Microsoft 365-centric organizations wanting native email security with XDR integration and cost efficiency through E5 licensing

Microsoft Defender for Office 365

The natural choice for Microsoft 365 environments, especially E5 customers who get it included in their license. Native XDR integration with Microsoft Defender correlates email threats with identity, endpoint, and cloud signals. Best for Microsoft-centric organizations wanting cost-efficient, ecosystem-integrated protection.

Cloud

Organizations wanting capable email security integrated with Trend Micro's broader Vision One XDR platform

Trend Micro Email Security

Cloud-native email security with the innovative Writing Style DNA feature for BEC detection and integration with Trend Micro Vision One XDR. Protects both Microsoft 365 and Google Workspace. Best for organizations using the Trend Micro security ecosystem who want competitive pricing.

Cloud

Mid-to-large enterprises wanting a unified email security, archiving, and continuity platform with strong API integrations

Mimecast

Cloud-delivered comprehensive email security with the added benefit of email continuity. While also listed under enterprise gateways, Mimecast is fully cloud-native and competes directly with Proofpoint for cloud-first organizations wanting archiving, DLP, and awareness training in one platform.

Cloud

Microsoft Defender for Office 365

Email Security
Best fit for

Microsoft 365-centric organizations wanting native email security with XDR integration and cost efficiency through E5 licensing

Microsoft Defender for Office 365 is Microsoft's native email security solution that provides protection against phishing, malware, and business email compromise for Microsoft 365 environments. It integrates deeply with the Microsoft security ecosystem including Microsoft Sentinel, Defender XDR, and Entra ID to provide cross-domain threat detection and automated investigation. For organizations heavily invested in Microsoft 365, Defender for Office 365 offers strong protection without requiring a third-party email security gateway.

Pricing

Plan 1 $2.00/user/month, paid yearly / Plan 2 $5.00/user/month, paid yearly / included in Microsoft 365 E5

Per-user subscription (bundled with Microsoft 365 E5)

Deployment

Cloud

Visit Microsoft Defender for Office 365View listing

Trend Micro Email Security

Email Security
Best fit for

Organizations wanting capable email security integrated with Trend Micro's broader Vision One XDR platform

Trend Micro Email Security is a cloud-hosted email gateway that protects against phishing, BEC, ransomware, and advanced malware targeting email channels. Part of Trend Micro's broader Vision One platform, it leverages Trend Micro's extensive global threat intelligence network and integrates with XDR capabilities for cross-layer detection. Its Writing Style DNA technology uses AI to detect BEC attacks by analyzing the writing patterns of executives and flagging emails that deviate from established styles.

Pricing

Custom pricing / per-user licensing

Per-user subscription

Deployment

Cloud

Standards & certifications

ISO 27001, SOC 2 Type II

Visit Trend Micro Email SecurityView listing

Mimecast

Email Security
Best fit for

Mid-to-large enterprises wanting a unified email security, archiving, and continuity platform with strong API integrations

Mimecast is a cloud-based email security platform that provides comprehensive protection against advanced email threats including phishing, ransomware, impersonation attacks, and business email compromise. Its Targeted Threat Protection suite uses multiple detection layers including URL rewriting, attachment sandboxing, and impersonation detection to block threats before they reach the inbox. Mimecast also offers email continuity, archiving, and security awareness training, positioning it as a direct competitor to Proofpoint across the full email security lifecycle.

Pricing

Custom pricing / per-user licensing

Per-user subscription

Deployment

Cloud

Standards & certifications

ISO 27001, SOC 2 Type II, ISO 27701

Visit MimecastView listing

Comparisons

Microsoft Defender for Office 365 vs Acronis Email Security

Choose Microsoft Defender for Office 365 if you are Microsoft 365-centric, hold or plan E5 licensing, and want native pr...

Read Comparison

Proofpoint vs Mimecast

Choose Mimecast if email continuity is critical and you want a well-rounded platform that is somewhat easier to administ...

Read Comparison

Abnormal AI vs Mimecast

Choose Abnormal Security if strong detection of socially-engineered attacks with no malicious payload is your priority a...

Read Comparison

Abnormal AI vs Trend Micro Email Security

Choose Abnormal Security if strong detection of socially-engineered attacks with no malicious payload is your priority a...

Read Comparison

Mimecast vs Trend Micro Email Security

Choose Mimecast if email continuity keeps mail flowing during outages. Unique differentiator is your priority and mid-to...

Read Comparison

Abnormal AI vs Microsoft Defender for Office 365

Choose Abnormal Security if strong detection of socially-engineered attacks with no malicious payload is your priority a...

Read Comparison

Shortlists

Editorial lists and deep dives covering these tools.

Frequently Asked Questions

For many organizations, particularly those with Microsoft 365 E5 licensing, Defender for Office 365 provides sufficient protection and eliminates the cost of a separate gateway. Microsoft has invested heavily in its email security capabilities and the native XDR integration is a genuine advantage. However, Proofpoint still leads in detection of advanced, targeted threats. Particularly sophisticated BEC campaigns and novel phishing attacks. Organizations in high-risk industries or those facing nation-state threats generally benefit from Proofpoint's superior detection and threat intelligence.

Microsoft Defender for Office 365 only protects Microsoft 365 environments. For Google Workspace protection, Trend Micro Email Security and Mimecast both offer cloud-native integration. Abnormal Security and IRONSCALES also protect Google Workspace via API. If you use Google Workspace, your primary cloud email security options are Trend Micro, Mimecast, or an API-based solution like Abnormal Security. Proofpoint also supports Google Workspace through its gateway deployment.

XDR integration allows email security to correlate threats across email, identity, endpoint, and cloud domains. For example, Microsoft Defender for Office 365 can detect that a phishing email arrived, the user clicked the link, credentials were entered on a fake page, and a suspicious sign-in occurred from a new location. Automatically triggering remediation across all layers. Proofpoint achieves similar correlation through API integrations with third-party XDR platforms, but native integration in the Microsoft and Trend Micro ecosystems provides tighter, faster cross-domain response.

Microsoft 365 and Google Workspace include baseline email security, but it historically has not matched the detection efficacy of dedicated email security platforms. Microsoft Defender for Office 365 Plan 2 has closed much of this gap for Microsoft environments. The decision depends on your threat landscape: if you face standard phishing and malware, your provider's built-in security (especially Microsoft E5) may suffice. If you face advanced targeted attacks, BEC, or need archiving and compliance, a dedicated platform like Proofpoint provides demonstrably better protection.

View all Email Security tools

About this listing

Cloud Email Security Platforms tools, compared on public information. The comparison table and the full entries follow our editorial order, with any paid Featured listing shown first and labelled. How we work →