Thunderbird 151 is now available as the latest update to Mozilla’s desktop email client. The primary update is support for Thundermail OAuth sign-in with automatic account configuration. Users can now override OAuth provider details for EWS accounts, providing greater control over Exchange Web Services setup.
Thunderbird 151 also restores the default application check at startup. Additionally, public keys are no longer attached by default to signed-only OpenPGP messages, reducing unnecessary attachments in unsigned mail. Plus, Tasks now offer sorting by creation or modification date.
Search functionality has been improved as Thunderbird 151 now restores the result count for ‘Find in Message’ and resolves issues where older, irrelevant emails appeared before newer, relevant matches.
Mail handling updates address IMAP messages displaying the correct received date, preserves formatting when replying with selected text in HTML messages, and fixes issues with malformed forwarded MIME emails producing empty bodies or extra attachments.
Regarding attachment handling, multipart/related attachments are now preserved when editing or forwarding messages, and on macOS, dragging attachments out of Thunderbird no longer creates duplicate copies.
Account Hub has received multiple fixes as well. Thunderbird 151 resolves Outlook setup failures after password prompts following OAuth login, ensures auto-discovered values are preserved for manual editing, corrects encryption and signature account links, and restores the OWL add-on description in non-English locales.
Calendar and task features have been updated. Calendar view tabs are now accessible via keyboard, date-only all-day tasks can be created, the task context menu no longer displays disabled items, and the ‘Current Tasks’ view now shows only unfinished tasks.
Additional fixes address newsgroup posting cancellation, POP3 virtual folder updates for filtered messages, command-line compose handling with double quotes, large messages incorrectly marked as read, and general visual and user experience improvements.
For more details, see the release notes. Thunderbird 151 is available for direct download on Windows 10 and newer, macOS 10.15 and later, and Linux systems from thunderbird.net.
