Comparison
Microsoft Defender for Office 365 vs Sublime Security
Microsoft Defender for Office 365
The BEC baseline you may already be paying for inside Microsoft 365
VERIFIED JUL 7, 2026
Sublime Security
Serious BEC defense a small team can actually turn on: free for 100 mailboxes, no MX change
VERIFIED JUL 7, 2026
| Pricing model | subscription | freemium |
| Starting point | Bundled into Microsoft 365 Business Premium ($22/user/mo), so many SMBs already own Plan 1 | Genuinely free for your first 100 mailboxes, no credit card and no MX change |
| Best for | Microsoft 365 shops that should turn on and tune the BEC-relevant protection they already own before buying anything dedicated. | Small and mid-size teams on Microsoft 365 or Google Workspace that want serious, tunable BEC and payroll-diversion protection they can turn on for free and grow into. |
| Countries | United States, United Kingdom, Canada, Australia | United States, United Kingdom, Canada, Australia |
| Editorial score | 7/10 | 8.4/10 |
Microsoft Defender for Office 365
Pros
- You may already own Plan 1 inside Business Premium, protection you've paid for and can simply switch on
- Native to Microsoft 365, so there's no third-party routing or MX change to deploy
- Covers the broad email threat surface (malware, malicious URLs, impersonation), not only BEC
Cons
- A broad email-security add-on, not a purpose-built behavioral payroll-diversion tool
- The payload-free 'change my direct deposit' email is where behavioral specialists (Sublime, Abnormal) still catch more
- Real value takes configuring the anti-phishing and impersonation policies, the defaults alone leave gaps
Sublime Security
Pros
- A real free tier (100 mailboxes) and no MX change, so a small team can switch it on today without a security project
- The open engine shows you why a message was flagged and lets you tune it, no black box
- Targets the behavioral tells of payroll-diversion BEC, the payload-free attacks a spam filter waves through
Cons
- Above 100 mailboxes pricing is quote-based, with no public number to compare against
- Detections-as-code only pays off if someone on your side will actually use it
- Still an email-security layer, it stops the request landing convincingly, it doesn't audit payroll records
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