Thunderbird 91.1.1

What's new in this version:

New:
- Menu item for disabling subject encryption for a single message added

Changed:
- Printing messages that are not currently displayed is no longer supported, including printing multiple messages at once

Fixed:
- Buttons on compose window dialogs did not have a visual indication of focus
- Dropdown fields in message compose window were unreadable on Windows 7 with a dark theme
- Multiple bulk mail notification warnings were displayed
- Enabled/Disabled state of message filters did not persist as expected
- Printing a message did not print a list of its attachments
- Images attached from a web page were not sent as expected
- OpenPGP public key was attached multiple times when forwading a message
- Windows tray icon disappeared if Thunderbird was started by a shortcut with "Run" set to "Minimized"
- Windows tray message count badge displayed the "unread" count instead of the "new" message count
- Some downstream Thunderbird builds were incorrectly checking addons for a signature, causing all addons to be disabled
- Addressbooks set up with autoconfig showed no search results
- Various CardDAV setup and auto-detection fixes
- Dates (such as birthday) stored in contacts may display the wrong date; a one-time manual fix may be needed for dates that are incorrect.
- Attached VCards displayed as plain text when an email was HTML formatted
- Mailing list names with non-ASCII characters incorrectly displayed with an error
- LDAP directories were not searched for matches when adding recipients to an email
- Clicking "Connect to an LDAP address book" in account setup opened CardDAV setup dialog
- LDAP address books using Kerberos/GSS-API authentication did not authenticate
- LDAP search queries containing non-ASCII characters produced no results
- IRC server connections did not automatically retry after a timeout
- Calendar event editor did not honor mail.spellcheck.inline