# Microsoft Defender for Office 365 vs ThreatDown Email Security: side-by-side comparison (2026)

[Microsoft Defender for Office 365](https://cybersectools.com/tools/microsoft-defender-for-office-365) is a commercial [email security platforms](https://cybersectools.com/categories/email-security-platforms) solution by [Microsoft](https://cybersectools.com/companies/microsoft). [ThreatDown Email Security](https://cybersectools.com/tools/threatdown-email-security) is a commercial [email security platforms](https://cybersectools.com/categories/email-security-platforms) solution by [ThreatDown by Malwarebytes](https://cybersectools.com/companies/threatdown-by-malwarebytes). Features, integrations, deployment and the company behind each one, side by side.

## Our take

What our shortlists say about the one we picked.

### [Microsoft Defender for Office 365](https://cybersectools.com/tools/microsoft-defender-for-office-365)

Best for: Teams running Microsoft 365

It is on the list because it is built into Microsoft 365, and many companies already own it through their license, so the buying question is often settled before you start. That makes it the natural first layer if you run Microsoft 365. Decide whether it covers your risk alone or needs a second product beside it, since it is built to work with other email security products.

From [Best Email Security Solutions for Business](https://cybersectools.com/shortlists/best-email-security-platforms), Fall 2026.

Reviewed by [Nika (Nikoloz) Kokhreidze](https://cybersectools.com/about).

Need the answer fast? [Best Email Security Solutions for Business](https://cybersectools.com/shortlists/best-email-security-platforms) picks Proofpoint Core Email Protection, Microsoft Defender for Office 365, Mimecast Advanced Email Security and 4 more.

## Side-by-side comparison

| | Microsoft Defender for Office 365 | ThreatDown Email Security |
|---|---|---|
| Pricing model | Commercial | Commercial |
| Category | Email Security Platforms | Email Security Platforms |
| Verified | No | No |
| Deployment type | Cloud | Cloud |
| Company size fit | SMB, Mid-Market, Enterprise | SMB, Mid-Market, Enterprise |
| Company | Microsoft | ThreatDown by Malwarebytes |
| Headquarters | – | – |

### Use cases and capabilities

| | Microsoft Defender for Office 365 | ThreatDown Email Security |
|---|---|---|
| Microsoft 365 | Yes | – |

### Core features

**Microsoft Defender for Office 365**

10 features listed. Sign in on the page to see them.

**ThreatDown Email Security**

8 features listed. Sign in on the page to see them.

### Integrations

**Microsoft Defender for Office 365**

4 integrations listed. Sign in on the page to see them.

**ThreatDown Email Security**

No integrations listed.

## Microsoft Defender for Office 365 vs ThreatDown Email Security FAQ

Common questions when comparing Microsoft Defender for Office 365 vs ThreatDown Email Security for email security platforms.

### What is the difference between Microsoft Defender for Office 365 and ThreatDown Email Security?

**Microsoft Defender for Office 365**: Email and collaboration security for Microsoft 365 environments. Built by Microsoft.

**ThreatDown Email Security**: AI-powered email security platform for phishing and BEC protection. Built by ThreatDown by Malwarebytes.

The table above shows where their features, integrations, deployment and company size fit differ.

### Who makes Microsoft Defender for Office 365 and ThreatDown Email Security?

**Microsoft Defender for Office 365** is made by Microsoft. **ThreatDown Email Security** is made by ThreatDown by Malwarebytes. The vendor behind a product decides its roadmap, support, and longevity, so check each company's profile before you commit.

### Is Microsoft Defender for Office 365 a good alternative to ThreatDown Email Security?

Often, yes. Microsoft Defender for Office 365 and ThreatDown Email Security are both Email Security Platforms products. Use the table above to see where features, deployment and company size fit differ.

## Related comparisons

- [Microsoft Defender for Office 365 vs Cisco Secure Email Threat Defense](https://cybersectools.com/compare/cisco-secure-email-threat-defense-vs-microsoft-defender-for-office-365)
- [Microsoft Defender for Office 365 vs KnowBe4 Cloud Email Security](https://cybersectools.com/compare/knowbe4-cloud-email-security-vs-microsoft-defender-for-office-365)
- [Microsoft Defender for Office 365 vs ConnectWise Email Security](https://cybersectools.com/compare/connectwise-email-security-vs-microsoft-defender-for-office-365)
- [ThreatDown Email Security vs Cisco Secure Email Threat Defense](https://cybersectools.com/compare/cisco-secure-email-threat-defense-vs-threatdown-email-security)
- [ThreatDown Email Security vs KnowBe4 Cloud Email Security](https://cybersectools.com/compare/knowbe4-cloud-email-security-vs-threatdown-email-security)
- [ThreatDown Email Security vs ConnectWise Email Security](https://cybersectools.com/compare/connectwise-email-security-vs-threatdown-email-security)

## Alternatives to each

- [See all Microsoft Defender for Office 365 alternatives](https://cybersectools.com/alternatives/microsoft-defender-for-office-365)
- [See all ThreatDown Email Security alternatives](https://cybersectools.com/alternatives/threatdown-email-security)

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Source: https://cybersectools.com/compare/microsoft-defender-for-office-365-vs-threatdown-email-security

For AI agents: each product above has its own Markdown page (add .md to its URL, for example https://cybersectools.com/tools/microsoft-defender-for-office-365.md). Every CybersecTools shortlist is listed at https://cybersectools.com/shortlists.md.

More on Microsoft Defender for Office 365 and ThreatDown Email Security: funding, momentum, hiring and news, plus the full product and company record, are available through the Mandos MCP Server (paid plans), which connects to AI assistants: https://mandos.io/mcp?utm_source=cybersectools.com&utm_medium=compare-md