Thunderbird 78.0 Release Imminent

MZLA Technologies Corporation has uploaded Thunderbird 78.0 to the distribution server; this means that the new major version of the email client will be released soon.
Update: The release notes are up now. The new version of Thunderbird is offered as a direct download only, and not as an upgrade from within the client itself. The team notes that users of Enigmail should not update, that only MailExtensions will work, and that OpenPGP functionality is disabled by default.
Thunderbird 78.0 is a major release which will replace the current stable branch, Thunderbird 68.x, in the future. The release notes are not up yet, but the beta release notes provide a good overview of the major changes in that release.
Attention: Thunderbird 78 makes major changes to the extension system similarly to the changes that Mozilla implemented some time ago in the Firefox web browser. Many extensions may not work anymore after the upgrade to Thunderbird 78 as classic extensions need to be updated to stay compatible. We suggest that you test a portable version of Thunderbird 78 first, e.g. by installing the add-ons that you rely on manually, to find out which extensions are compatible and which are not.
Thunderbird 78.0
The development team released four beta versions before the final release. The beta release notes list major changes in each of the beta versions.
New Features
- New Account Hub for centralized account setup.
- Color customization of Folder Pane icons.
- Additional Enterprise policies.
- Preferences to disable OpenPGP functionality.
- Calendar: add event preview to ICS import dialog.
- MailExtensions: browser.identity API enabled.
- MailExtensions: event fired when the user changes compose identity.
- MailExtensions: UI components for browser pages added.
- Chat: direct message support for Matrix.
Changes:
- OpenPGP support improvements.
- OpenPGP improvements
- Various address book improvements.
- Dark Mode improvements.
- Use scalable icons throughout Thunderbird.
- Account settings UI improvements.
- Improvements to the location bar of a tab displaying web pages.
- Several improvements to vCard parsing.
- Various look and feel improvements.
- MailExtensions: Handle message attachments in browser.compose functions
- Calendar: location URLs are now clickable.
Fixes:
- Various fixes for recipient address entry
- Fixed width font not working in Write window
- Accessibility improvements
- Attachment pane in message preview layout broke when toggled or resized.
- Access key Alt-M for the attachment pane of the Write window not working correctly.
- Addons could not be removed.
- Print-progress dialog was disabled.
- Clear Recent History window did nothing.
- Initially Show Attachment Pane option was not working for Write window.
- Links in the Account Central content tab opened in Thunderbird as well as the browser.
- Order of columns in the thread pane was not persisted correctly.
- URLs in the message header display were not reachable via keyboard.
- Calendar: URLs in the event reminder dialog were not clickable
- MailExtensions: Extension popup windows opened in a copy of the main window.
- OpenPGP support did not work on some Linux distributions when using the official builds.
- Thunderbird 78 did not run on Red Hat Linux 7.
- Anomalies appeared when inserting an image into the compose window
- Chat: copying from chat conversations not working.
- Addresses added to address book were not inserted into sorted order.
- Address book migration not working under certain circumstances.
- Chat: own messages not displayed in private chats when server supports "echo message".
- MailExtensions: Tab was not defined in browser.menus.onClicked callback on out-of-window messages.
- MailExtensions: select elements in action popups closed the window unexpectedly.
Closing Words
It is too early for a final verdict; the final release notes are not out and there is a chance that other things have changed, were fixed, or introduced in the new version.
Users who rely on certain add-ons may want to wait with the upgrade.
Now You: Do you use Thunderbird? Will you upgrade right away to the new version?


You said that Outlook isn’t your main email client, so which is your main one?
I think its thunderbird
It is Mozilla Thunderbird.
Awesome! This actually solved my problem… what a stupid bug.
If this is the same bug that I’ve encountered, there may be another fix: (1) hover over open Outlook item in Taskbar, cursor up to hover over Outlook window item, and right-click; (2) this should give you Restore / Move / Size / Minimize / Maximize — choose Move or Size; (3) use your cursor keys, going arbitrarily N/S/E/W, to try to move or size the Outlook window back into view. Basically, the app behaves as though it were open in a 0x0 window, or at a location that’s offscreen, and this will frequently work to resize and/or move the window. Don’t forget to close while resized/moved, so that Outlook remembers the size/position for next time.
THANK YOU Claude!!! I could get the main window to launch but could not get any other message window to show on the desktop. You are my hero!!!!
Solved my issue! 6 years later and this is still problem…
Fantastic. Thank you. Size did the trick.
This solved my Outlook problem, too. Thank you. :)
Thank you so much, this started happening to me today and was causing big problems. You are a life saver, I hope I can help you in some way some day.
You are a god – thank you!
thanks a lot…. work like charm.. :-)
Yah…thanks Claude. I’ve been having the same problem and tried all the suggestions…your solution was the answer. It had resized itself to a 0/0 box. Cheers
Excellent post. This had me baffled even trying to accurately describe the problem. This fixed it for me.
Thank you
Thanks a lot for the article. Don’t know why it happenend, don’t know how it got fixed, but it was really annoying and now it works :-)
Thanks a lot. I was facing this issue from past 3 week. I tried everything but no resolution. The issue was happening intermittently and mainly when I was changing the display of screen ( as i use 2 monitors). The only option i had was to do system restore. But thanks to you.
I’ve been tried to sole this problem for 12hours. Your comment about changing the display of screen helped me a lot!! Thanks!!
Thank you…don’t know why this happened but your instructions helped me fix it. Running Windows 10 and office pro 2007
Great tip! Thanks!
Worked for me, too – thank you!!!
It’s Worked for me, too
thank you very much!
I had a similar issue with Outlook 2013 on Windows 10 and this helped me to fix it. Thank you very much!
Thank you so much. Solved!
Considering you published this in 2012, incredible not been debugged by Microsoft.
Thank you again. M
This problem was faced by only one user logging to TS 2008 r2 using outlook 2010.The issue was resolved.
Thanks.
Great tip. Thank you!!!! If it helps, I had to use the Control Key and the arrow keys at the same time to bring my window back into view. Worked like a charm.
Thank you, this worked !!!!
Man, you are a fucking god. Thanks a lot, what an annoying bug!!
Awesome, this post solved the issue. Many thanks!