Thunderbird 152.0

Thunderbird is a fast, flexible email client featuring add-ons, smart search, advanced filtering, RSS, and full IMAP/POP support.

Razvan Serea News Reporter Neowin · Jun 17, 2026 13:38 EDT with 0 comments

Thunderbird

Thunderbird is a free, open-source, cross-platform application for managing email and news feeds. It is a local (rather than a web-based) email application that is powerful yet easy-to-use.

Thunderbird is clean and elegant by default, but easily customizable to match your workflow and visual preferences. It is loaded with unique and powerful features.

Thunderbird is developed, tested, translated and supported by the folks at Mozilla Corporation and by a group of dedicated volunteers. Thunderbird gives you control and ownership over your email. There are lots of add-ons available for Thunderbird that enable you to extend and customize your email experience.

Thunderbird gives you IMAP/POP support, a built-in RSS reader, support for HTML mail, powerful quick search, saved search folders, advanced message filtering, message grouping, labels, return receipts, smart address book LDAP address completion, import tools, and the ability to manage multiple e-mail and newsgroup accounts.

Thunderbird 152.0 changelog:

SecurityDevices enabled in enterprise policies
One-click account setup for Thundermail accounts

What’s Changed

Use 'Add' instead of 'New' for account, calendar, address book creation buttons
GMail OAuth updated to use PKCE
Mail server hostname also checked when detecting address books and calendars
Updated about:rights to replace local with hosted url
'Hide completed tasks' now also hides cancelled tasks

What’s Fixed

New mail alerts appeared on wrong monitor in three-monitor setup
Spam messages triggered new mail notifications before being moved to Spam folder
Filtered IMAP or NNTP subscriptions were lost after closing Subscribe dialog
'Download Headers' dialog for newsgroups failed to open
Messages nested deeper than 255 levels disappeared from threading view
Performing Delete followed by Undo on thread parent message could corrupt view
Single messages still appeared collapsible after thread members were deleted
Updated threads remained misordered until folder refresh or resort
Non-threaded subject sorting separated 'RE:' replies from original messages
BCC recipients were included in signed email headers
Filter search on Body missed draft messages containing German umlauts
Thunderbird could crash during local message search
Blocked file warning showed without 'Unblock File' button in compose window
Forwarding/Redirecting Exchange messages failed with NS_ERROR_OUT_OF_MEMORY
Compose window closed early and send progress dialog hung after NNTP failure
Compose window stayed open after sending when mailnews.sendInBackground set
Microsoft OAuth2 failed when HTTPS localhost redirect was not intercepted
Pasting contact photos stopped working when photo button had focus
Filter dialog lacked focus ring and had poorly distinguishable buttons
Subfolder kept stale accessibility unread count after unread messages were deleted
'Edit as New Message' and inline 'Forward' not possible with PGP-signed messages
Various MIME improvements
EWS messages could go missing from folder view
IMAP "Show only subscribed folders" could not be changed without restart
Unable to delete more than 1000 messages at a time on Microsoft 365
EWS folders in Trash were moved to Trash again instead of being hard deleted
IMAP notifications repeated for emails read on another device after sleep wake
POP3 deadlocked when server went silent without closing socket
Calendar acceptance no longer distinguished between single occurrence and series
Transparent popups on macOS made calendar event editing difficult
Duplicate attendees were added to invitations instead of being filtered out
Task percentage complete was not preserved separately from status in tooltips
Visual and UX improvements
Security fixes