• DeveloperMozilla Thunderbird
• LicenseFree
• Size—
• UpdatedOct 31, 2026

Mozilla Thunderbird ESR

Thunderbird is a free and open source email, newsfeed, chat, and calendaring client, that’s easy to set up and customize. One of the core principles of Thunderbird is the use and promotion of open standards - this focus is a rejection of our world of closed platforms and services that can’t communicate with each other. We want our users to have freedom and choice in how they communicate.

This is the official annual extended support release. This release is intended for users who want all available new features on an annual basis and stability/security fixes on a monthly basis.