Acronis Email Security vs Microsoft Defender for Office 365
Microsoft Defender for Office 365 is Microsoft's native email security for Microsoft 365, bundled into E5 licensing with deep XDR integration. Acronis Email Security is a third-party layer that scans Microsoft 365, Google Workspace, and other mailboxes, sold as an add-on to Acronis Cyber Protect Cloud with backup, endpoint protection, and DLP on the same platform. The core trade-off: native integration and bundled economics versus an added detection layer with broader mailbox coverage and MSP-oriented management.
Updated Jul 2026Summary
Choose Microsoft Defender for Office 365 if you are Microsoft 365-centric, hold or plan E5 licensing, and want native protection inside Microsoft's XDR stack with no additional vendor. Choose Acronis Email Security if you want a specialised layer on top of native defences, need Google Workspace or mixed-mailbox coverage, or are an MSP consolidating email security with backup, endpoint protection, and DLP under multi-tenant management. Note the SE Labs figures cited here come from a test in which both products participated; verify current detection performance for your own mail profile with a trial.
Choose Acronis Email Security if:
- You are standardised on Microsoft 365 and already licensed for E5, making Defender effectively bundled
- You want native integration with Microsoft's XDR stack (Defender for Endpoint, Sentinel) without a third-party vendor
- You prefer fewer vendors and accept Microsoft-native protection as sufficient for your threat profile
- You do not need coverage for Google Workspace or non-Microsoft mailboxes
Choose Microsoft Defender for Office 365 if:
- You want a second, specialised detection layer on top of Microsoft 365's native defences
- You need coverage across Microsoft 365, Google Workspace, and other mailboxes in one product
- You are an MSP wanting multi-tenant management with backup, endpoint protection, and DLP on the same platform
- You value an included incident response service for investigations and false-positive handling
- Independent testing matters to you: SE Labs rated it AAA with 94% total accuracy and zero false positives in its email security evaluation
Feature Comparison
| Feature | Acronis Email Security | Microsoft Defender for Office 365 |
|---|---|---|
| Deployment | Native to Microsoft 365, enabled via licensing | API-based Microsoft 365 provisioning, no MX-record changes; also Google Workspace and other mailboxes |
| Mailbox coverage | Microsoft 365 (Exchange Online, Teams, SharePoint, OneDrive) | Microsoft 365, Google Workspace, on-premises and other cloud mailboxes |
| Detection approach | Signature, reputation, and detonation (Safe Attachments/Safe Links) within Microsoft's stack | Multilayered: anti-spam, anti-evasion, anti-phishing, anti-spoofing, antivirus, threat intelligence, CPU-level dynamic detection (vendor-described) |
| Outbound scanning | Included for Microsoft 365 traffic | Included for Microsoft 365 via API |
| Incident response service | Not included (Microsoft support / paid add-ons) | Included: analyst investigations, false-positive handling, reporting |
| Independent testing | 28% total accuracy in the same SE Labs email security test (Office 365 ATP, as tested) | #1 in SE Labs email security evaluation: AAA rating, 94% total accuracy, zero false positives |
| Platform scope | Part of Microsoft Defender XDR | Part of Acronis Cyber Protect Cloud (backup, DR, endpoint protection, DLP) |
| Pricing model | Per-user subscription; bundled with Microsoft 365 E5 | Per unique protected mailbox/user, add-on to Acronis Cyber Protect Cloud; one-month trial |