Meet the contenders

Whether you're a freelancer, small business owner, or corporate executive, there's an email app for you. We're here to help you decide.

Let's look at how these two email apps stack up against each other.

Thunderbird

Thunderbird is a free, open-source, cross-platform email client that’s managed by a core staff and a community of volunteer developers. Although the app is already quite robust, there are optional add-ons that you can install to enhance its functionality. So, when it comes to cost-effective email client apps, you can’t go wrong with free—there are no separate paid versions.

Outlook for Windows

Outlook for Windows is a new email client and personal information manager that replaces the defunct Windows Mail and Calendar apps (which are no longer supported by Microsoft). This default email client app is included in most newer Windows 11 PCs shipped in 2024 and features tight integration with Microsoft 365 apps, AI tools, and a fresh design.

Thunderbird vs Outlook for Windows: A side-by-side comparison

	Thunderbird	Outlook for Windows
Operating system	WindowsmacOSLinuxAndroid	Windows
Versions	Free	Outlook Free Microsoft 365 Basic Microsoft 365 Personal Microsoft 365 Family
Price(s)	Free	Outlook Free Microsoft 365 Basic: $19.99/year Microsoft 365 Personal: $99.99/year Microsoft 365 Family: $129.99/year
Notable features	Multi-account support Unified inbox Extensive library of add-ons End-to-end encryption (S/MIME and OpenPGP) Junk mail filtering Spam filtering Phishing protection Built-in chat Built-in newsgroup and RSS reader Tabbed email interface Customizable user interface Multi-language support (currently translated into 65 languages)	Multi-account support Simplified interface, with modern design Integration with Microsoft 365 tools Natural-language search capabilities AI-assisted email authoring with Microsoft Copilot Third-party app integrations Customizable user interface Collaboration tools Offline support Built-in translation for email messages in over 70 languages