Best Cloud Email Security Alternatives to Proofpoint in 2026

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.