What’s New
• 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