Free and Open Source
Thunderbird is completely free to use and its source code is open to the public, allowing for community-driven development and transparency.
Customization
The application supports a variety of extensions and themes, enabling users to personalize their email client according to their preferences.
Cross-Platform
Thunderbird is available on multiple operating systems including Windows, macOS, and Linux, providing flexibility for users on different platforms.
Robust Security
Thunderbird offers strong security features such as built-in phishing protection, spam filters, and support for S/MIME and OpenPGP for encrypting email messages.
Integrated Calendar
The Lightning extension allows for efficient scheduling and includes calendar features directly within the email client.