# Microsoft Defender for Office 365 vs Sublime Security Sublime Rules: 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). [Sublime Security Sublime Rules](https://cybersectools.com/tools/sublime-security-sublime-rules) is a free [detection engineering](https://cybersectools.com/categories/detection-engineering) solution by [Sublime Security](https://cybersectools.com/companies/sublime-security). 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 | Sublime Security Sublime Rules | |---|---|---| | Pricing model | Commercial | Free | | Category | Email Security Platforms | Detection Engineering | | Verified | No | No | | Deployment type | Cloud | On-Premises | | Company size fit | SMB, Mid-Market, Enterprise | Startup, SMB, Mid-Market, Enterprise | | Company | Microsoft | Sublime Security | | Headquarters | – | – | ### Use cases and capabilities | | Microsoft Defender for Office 365 | Sublime Security Sublime Rules | |---|---|---| | Microsoft 365 | Yes | – | | Detection Rules | – | Yes | | Open Source | – | Yes | | YARA | – | Yes | ### Core features **Microsoft Defender for Office 365** 10 features listed. Sign in on the page to see them. **Sublime Security Sublime Rules** 10 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. **Sublime Security Sublime Rules** No integrations listed. ## Which one fits you Based on what each listing shows: deployment, company size, price and open source. - [Microsoft Defender for Office 365](https://cybersectools.com/tools/microsoft-defender-for-office-365) fits if you want a cloud product. - [Sublime Security Sublime Rules](https://cybersectools.com/tools/sublime-security-sublime-rules) fits if you need to run it on your own servers, you are a startup, you need a free product and you want an open-source product. ## Microsoft Defender for Office 365 vs Sublime Security Sublime Rules FAQ Common questions when comparing Microsoft Defender for Office 365 vs Sublime Security Sublime Rules for email security platforms. ### What is the difference between Microsoft Defender for Office 365 and Sublime Security Sublime Rules? **Microsoft Defender for Office 365**: Email and collaboration security for Microsoft 365 environments, built by Microsoft. **Sublime Security Sublime Rules**: Open-source detection rules for email attacks like BEC, phishing, and malware, built by Sublime Security. The table above shows where their features, integrations, deployment and company size fit differ. ### Who makes Microsoft Defender for Office 365 and Sublime Security Sublime Rules? **Microsoft Defender for Office 365** is made by Microsoft. **Sublime Security Sublime Rules** is open-source. 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 Sublime Security Sublime Rules? In part. Microsoft Defender for Office 365 and Sublime Security Sublime Rules are not in the same category on CybersecTools. Key differences: Microsoft Defender for Office 365 is Commercial while Sublime Security Sublime Rules is Free. 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) - [Sublime Security Sublime Rules vs Cisco Secure Email Threat Defense](https://cybersectools.com/compare/cisco-secure-email-threat-defense-vs-sublime-security-sublime-rules) - [Sublime Security Sublime Rules vs KnowBe4 Cloud Email Security](https://cybersectools.com/compare/knowbe4-cloud-email-security-vs-sublime-security-sublime-rules) - [Sublime Security Sublime Rules vs ConnectWise Email Security](https://cybersectools.com/compare/connectwise-email-security-vs-sublime-security-sublime-rules) ## Alternatives to each - [See all Microsoft Defender for Office 365 alternatives](https://cybersectools.com/alternatives/microsoft-defender-for-office-365) - [See all Sublime Security Sublime Rules alternatives](https://cybersectools.com/alternatives/sublime-security-sublime-rules) --- Source: https://cybersectools.com/compare/microsoft-defender-for-office-365-vs-sublime-security-sublime-rules 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 Sublime Security Sublime Rules: 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