Thunderbird 154.0 arrives with Microsoft Graph support and system tray hiding

On August 18, 2026, Mozilla released Thunderbird 154.0, the latest stable version of its free, cross-platform email and news feed client. Builds are available for Windows, macOS, and Linux via the Thunderbird Release channel. This is not an ESR release; users seeking a long-term support version can download Thunderbird 153.0.3 ESR (or 115.18.0 for Windows 7/8.1).

The previous ESR release, Thunderbird 140.0, was launched in early July 2025, while Thunderbird 153.0 ESR followed in July 2026. Updates for the ESR branch will be provided for one year.

Key changes and improvements in Thunderbird 154.0 include: — a new attachment preview feature for macOS; — correct decryption of CMS messages with AuthEnvelopedData; — global search results can now default to list view via a new setting; — a new "Copy to" context menu for message/rfc822 attachments; — an additional system tray mode that hides Thunderbird when the last window is closed; — support for dragging and dropping MIME message/rfc822 attachments into the folder tree; — Microsoft Graph integration is now enabled for Microsoft 365 accounts; — 32 bugs fixed since the previous stable build, along with security patches for previously disclosed vulnerabilities.