Microsoft Defender for Office 365 alternatives (2026)
8 cloud email security tools listed alongside Microsoft Defender for Office 365 for side-by-side comparison on capabilities, pricing, and deployment. No editorial ranking.
Acronis Email Security
FeaturedAcronis Email Security extends Defender's native Microsoft 365 protection with 100% content analysis of inbound and outbound traffic, deeper anti-evasion (recursive unpacking of embedded files/URLs), CPU-level zero-day detection, and integrated backup, endpoint protection, and DLP on one platform. API-based M365 provisioning, no MX-record changes.
Pricing: Subscription, add-on to Acronis Cyber Protect Cloud
Why look for Microsoft Defender for Office 365 alternatives?
Microsoft Defender for Office 365 is a strong option for cloud email security, but it's not the right fit for every team. Common reasons teams look elsewhere: only protects microsoft 365. does not support google workspace or other platforms; detection efficacy for advanced threats historically behind proofpoint and mimecast.
Below we list 8 alternatives, broken down by deployment model. All data is aggregated from official documentation and community feedback.