Thunderbird 158.0 Fixes a Pile of Calendar, Contact and Mail Annoyances
*A maintenance release that quietly stops your address books from forgetting passwords and your Ctrl+Enter from sending everything twice.
If you have ever hit Send and then watched the same message land twice because your finger lingered on Ctrl+Enter, version 158.0 of Thunderbird has a small gift for you. Released on October 13, 2026, it does not add headline features, but it clears out a surprisingly long list of everyday irritations.
Mail that behaves
Quick Filter now answers faster, and it finally matches accented names when you search without typing the accents. A crash that struck during body searches is gone, and right-clicking an inline image opens the context menu instead of zooming the picture. Copying the link of a detached attachment now gives you the full path rather than just a filename, and archived Inbox folders show their localized names instead of the bare word "INBOX".
Sending is tidier too. Holding Ctrl+Enter no longer confirms the send prompt and fires off duplicates, and plain-text inline forwards keep signatures where you put them, below the quoted text. Switching to Unified Folders no longer leaves "All Folders" enabled with nothing changing on screen.
Contacts and calendars you can trust
This is where the update shines for anyone syncing with a cloud provider. Saved CalDAV and CardDAV credentials are no longer forgotten after a restart, CardDAV setup now asks for a password, and newly added contacts actually arrive during sync. Updates no longer scramble vCard timestamps, and discovery copes with valid responses that mix several status codes. Calendar edits stop failing with a localization error, and password prompts finally say which username and calendar they belong to.
Privacy and encryption
Remote content exceptions written without a scheme now apply to both HTTPS and HTTP, and exceptions no longer wrongly let through wildcard hostnames such as *.example.com. For OpenPGP users, several key-management problems around unlocking, handle leaks and protection state are resolved, and the backup password text can be copied again.
Other repairs
RSS filtering no longer loses tags or stalls later items, POP accounts stop nagging with repeated connection errors when you start offline, and a Matrix single sign-on loop that reopened the login endlessly is cured. Security fixes are listed on Mozilla's vulnerability page for Thunderbird 158.
Our verdict
If you sync calendars or contacts over CalDAV or CardDAV, or you use OpenPGP, this is the one to grab now; the fixes there address problems that quietly eat your time. Everyone else benefits from the send-prompt fix and the security patches, so there is little reason to wait. It is a no-drama upgrade that makes the app feel more dependable.
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