Latest version of Thunderbird released

Thunderbird 155.0 Final

What’s New

S/MIME popup shows signature, digest, encryption algorithms and key sizes
Default address book for manually added contacts configurable with mail.addr_book.add_item_default_uri
Enterprise policy DisableQRExport can disable QR export
OAuth add-ons can override built-in settings for selected domains and hostnames
Manual account config streamlined with Exchange, Graph, and custom OAuth support
Custom OAuth support for IMAP and SMTP servers
PKCE and external browser fields added to custom OAuth settings
Enterprise policy DisableExperimentalFeatures for disabling experimental features

What’s Fixed

Unread count dock badge disappeared on macOS restart when no mail window opened
IMAP tags did not sync automatically across clients
Embedded SVG images appeared broken when Display Attachments Inline was disabled
Holding arrow keys failed to smoothly navigate the folder pane
Mark and Tag menu bar items were disabled in search results
Quick Filter ignored address book display names shown in message lists and headers
Attachment filters could disappear or return no results in global search
Body search failed for quoted-printable messages ending on a soft line break
Failed encrypted send did not preserve draft
Failed account setup left an incoming server that blocked account recreation
Removing an account did not remove its OAuth token from the password manager
Account Hub prompted for calendar credentials immediately after successful login
Filters could copy empty messages to Local Folders during startup mail download
Closing message filters wrongly warned completed newsgroup filters were running
Autoscroll icon was missing directional arrows in scrollable messages
Apple Mail text attachments may not appear in MIME messages
Forwarded messages could display incorrect encoding
Thunderbird could crash due to improper database memory handling
Thunderbird could crash on shutdown while waiting for OAuth2 password entry
Thunderbird could crash while loading mail folders
Custom OAuth could not be disabled
Legacy IMAP tag changes were not sent to the server and reverted after refresh
Deleting an Exchange account retained the outgoing server settings
CalDAV calendars with offline support could stop fully synchronizing events
Offline cached ICS calendar changes were silently lost after reconnecting
Thunderbird upgrade disabled composition toolbar
Thunderbird upgrade disabled Settings menu for versions before macOS 13
Windows jump list menu no longer functioned correctly
Visual and UX improvements

Security fixes