Thunderbird 68.0 Beta 2

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 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.

What's new in Thunderbird 68.0 Beta 2:

Run filters periodically. Improved filter logging.
"Off the record" (OTR) chat, see the Wiki
Support for the "CLIENTID" SMTP/IMAP command
File link attachments can now be linked to again instead of uploading them again
Added a policy engine that allows customized Thunderbird deployments in enterprise environments, using Windows Group Policy or a cross-platform JSON file
TCP keepalive for IMAP protocol

Changed:

Add-on support: Restartless add-ons and non-restartless legacy add-ons using XUL overlays are only supported if add-on authors have adapted them
Theme support: Thunderbird no longer supports so-called lightweight themes. Therefore none of the themes offered at addons.thunderbird.net currently work. Lightweight themes will be converted to WebExtension themes, but this conversion has NOT happened yet. It has happened at addons.mozilla.org. Workaround: Manually install from addons.mozilla.org by dragging the link or .xpi file into the Add-ons Manager.
Application menu aka "Hamburger menu"
Box.com file link provider was removed and is now available as add-on at ATN
UI improvements for external attachments
Improvements to scam warnings
Various UI improvements. Many changes affecting UI, and so problems are expected. Please file bug reports at bugzilla.mozilla.org.

Fixed:

Malfunction when deleting a message opened in a tab or stand-alone window
Blank new mail notification under some circumstances
Spellcheck marks disappeared erroneously for words with an apostrophe

Changed and Fixed in Beta 2:

Various theme improvements.
SMTP password wasn't removed when account was deleted or server or user name were changed
Chat: Context (right-click) menu and spelling. In each conversation an individual spellcheck language can be selected now.

Known Issues:

Chat: Ctrl+D and Ctrl+U not working to switch between conversations. Status selector not working.
Customising From address breaks saving draft and sending message
Thunderbird 68 beta may not recognise an existing profile. Workaround: start with the profile manager option -p.
Thunderbird 68 beta may display a message "You've launched an older version of Firefox" and will not allow opening a specific profile. Workaround: start with option --allow-downgrade.
Due to changes in the Mozilla platform profiles stored on Windows network shares addressed via drive letters are now addressed via UNC
Calendar: A localized version of Provider for Google Calendar not available at addons.thunderbird.net or the Mozilla FTP server. A US-English version can be downloaded here. The XPI file needs to be installed manually in Thunderbird.
Chat: Twitter not working due to API changes at Twitter.com