Thunderbird 68.x compatibility · Issue #171 · thsmi/sieve · GitHub


Thunderbird 68.3.0

Thunderbird 68.3 fixes several security vulnerabilities. You find detailed information about each on the official security advisories page. The email client is not affected by critical issues; the highest severity rating is high.


Here is a short list of fixed issues:

  • CVE-2019-17008: Use-after-free in worker destruction
  • CVE-2019-13722: Stack corruption due to incorrect number of arguments in WebRTC code
  • CVE-2019-11745: Out of bounds write in NSS when encrypting with a block cipher
  • CVE-2019-17009: Updater temporary files accessible to unprivileged processes
  • CVE-2019-17010: Use-after-free when performing device or
  • CVE-2019-17005: Buffer overflow in plain text serializerientation checks
  • CVE-2019-17011: Use-after-free when retrieving a document in antitracking
  • CVE-2019-17012: Memory safety bugs fixed in Firefox 71, Firefox ESR 68.3, and Thunderbird 68.3

The official release notes list two additions to Thunderbird 68.3.0. Extension developers may use the newly implemented Message Display Toolbar Action WebExtension API, and navigation buttons are now available in content tabs in the application.

Windows users who use Thunderbird may notice that the new email icon has changed on the system.

The remaining changes address issues in previous versions of the email client. None of the issues appear to be major, e.g. that attachment icons were not always correct in the write pane or that the drag & drop reordering of accounts was not working on the Instant messaging status dialog.


Users who noticed that toolbar buttons of add-ons would not show up in the menubar after start won’t experience that issue anymore in the new Thunderbird version.

Now You: which email client do you use?


Article NameEmail client Thunderbird 68.3.0 is out DescriptionThe Thunderbird team has released Thunderbird 68.3.0 recently. The update addresses several security issues and (mostly) bugs in the client. Author Martin Brinkmann Publisher Ghacks Technology News Logo



Thunderbird’s initial design

Portrait from Shin Megami Tensei: Strange Journey

Thunderbird in Persona 5 Royal

Thunderbird casting Mazionga in Shin Megami Tensei V

サンダーバード – 真・女神転生V 日めくり悪魔 Vol.079Thunderbird in SMTV Daily Demon #079


It’s important to note that the Thunderbird email problems discussed above often lead to functionality and performance inefficiencies. Considering that Thunderbird development has been unstable for a few years now, you should expect to experience issues regularly. It can be annoying to many users when an issue persists, even though most issues can be easily fixed. Save yourself the annoyance and try a new email client. Download Mailbird for free to make sure it fits your needs.

Get Mailbird and Check the Most Effective Way to Manage Your Email Accounts! Try Mailbird for Free

How do I fix my Thunderbird email?

You can fix your Thunderbird email issues by adequately setting up an email account, choosing the appropriate provider, looking into incoming and outgoing email issues, disabling add-ons, solving freezing issues, and solving IMAP server errors.

Why is my Mozilla Thunderbird not working?

One of the primary causes may be antivirus or firewall software preventing Thunderbird from delivering your valuable messages. Simply disabling the tools will serve the purpose.

Is Thunderbird email still supported?

Thunderbird is an open-source app, but it’s no longer upgraded and supported by Mozilla. There are various quality alternatives (e.g., Mailbird) present in the online sphere.

Why does Thunderbird keep freezing?

Thunderbird often freezes or hangs due to antivirus interference, problematic settings, or some program or service interference.

What should I do if I can’t connect to the mail server in Thunderbird? If this happens, first try to log into your account through a web browser. Then, restart the Thunderbird app and try to re-login. If this doesn’t work, you can also try enabling access to less secure apps via the security settings of your email account in the webmail interface. Or try adding Thunderbird as an exception in your antivirus program.

Classic Thunderbird Addon

The classic addon is badly broken for TB68 and up. Since last week support for “classic” addons was officially dropped by Thunderbird and the corresponding code was removed for Thunderbird’s code base. ()

So the classic addon is dead as dead could be. I also removed any code referring to the old classic add-on from the repository.

What does this mean for the future?

The chances for a new WebExtension based Thunderbird addon are currently looking better.

The future for “WebExtension Experiments” is still somehow unclear. You can read very different statements on the Thunderbird mailing list. But at least for the next one to two years they seem to be promised to stay. But there are sadly no guarantees. And if the experiments go await the addon will be also gone.

So the longterm focus will remain on the app.

Thunderbird in Various Cultures

Thunderbird of the Menominee Peoples

According to the Menominee tribe, the Thunderbirds live on an enormous mountain that floats in the sky. These majestic creatures are known to control the elements (rain, hail, etc.) and sometimes watch the happenings of human life. They are said to find great pleasure in fighting and the accomplishment of impressive feats. These Thunderbirds are known to be enemies of the Misikinubik (The Great Horned Snake) and are the reason mankind has not been devoured or overrun.

The Menominee Thunderbirds are also known to be messengers of the Great Sun and were highly respected by these peoples.

Thunderbird of the Ojibwe Peoples

The Ojibwe legends of the Thunderbird claim this creature was created by Nanabozho (one of the culture’s hero figures) in order to protect people from evil underwater spirits. They lived in the four directions and migrated to the land of the Ojibwe during the spring with other birds. During this time they fought the underwater spirits. They stayed until the fall when the most dangerous season for the underwater spirits had passed. In the fall, they migrated south with other birds.

The Ojibwe Thunderbird legends also suggest that these creatures were responsible for punishing humans who broke moral rules. As the anger of the Thunderbird is known to be extreme, this would have been great incentive to maintain good moral conduct.

Thunderbird of the Winnebago Peoples

The Thunderbird of the Winnebago people suggests that this creature also had the power to grant people great abilities. Their traditions dictate that any man who has a vision of the Thunderbird during a fast will one day become a mighty war chief.

Thunderbird of the Sioux Peoples

Sioux legends claim that the Thunderbird was a noble creature that protected humans from Unktehila during the ‘old times.’ The Unktehila were said to be extremely dangerous reptilian monsters – without the help of the Thunderbird it is uncertain if man would have been able to overcome these creatures alone.

Thunderbird of the Arapaho Peoples

Arapaho mythology sees the Thunderbird as a summer creature (as did many of the tribes of the Great Plains). According to their legends, the Thunderbird was an opposing force to the White Owl (the creature that represented winter).

Thunderbird of the Algonquian Peoples

The Algonquian Peoples had deep reverence for the Thunderbird in their culture. According to their legends, Thunderbirds were ancestors of the human race. Their stories often tell of the Thunderbird’s part in the creation of the universe.

According to their myths, Thunderbird ruled over the upperworld and the Great Horned Serpent ruled over the underworld. Thunderbird protects humans from the Great Horned Serpent and its followers by throwing lighting at underwater creatures.

Thunderbird of the Shawnee Peoples

Like many other tribes, the Shawnee people also believed the Thunderbird could change its appearance in order to interact with people. Their beliefs, however, detail that Thunderbirds appeared as boys and could be identified by their tendency to speak backwards.

Thunderbird Troubleshooting: Common Thunderbird Email Problems

Despite the simple and highly efficient nature of Thunderbird, users may occasionally face a few performance issues and errors. Let’s take six common Thunderbird email problems and their solutions into consideration.

Email Account Setup Issues

While setting up the email account, some users may face operational issues like Thunderbird not connecting to the server. You can quickly fix the problem as follows.

1. Check Password

First, check if you’re using the correct password by logging into your account via the webmail interface. For example, if you have a Gmail account:

  1. Go to
  2. Type your email address and then your password.
  3. If you’ve input an older password, Google will prompt you to reset it.
  4. You can reset your password by clicking the “Forgot email?” message.
2. Check Server Settings

If your password is correct or you set a new one and problems persist, go to Thunderbird and launch the Server Settings. You can find them following this path:

  1. Click on the email account that experiences issues.
  2. Under Options click on Account Settings.
Select Server Settings in the left-hand tab.
  1. Select Server Settings in the left-hand tab.
To make sure you have the correct server settings,

To make sure you have the correct server settings, take the following details into account.

  1. Have the domain name (e.g., after the server name, which is Mail.
  2. Make sure Port is 993 for IMAP or 995 for POP.
  3. Set the Connection Security to TLS/SSL.
  4. Use the user’s full email address as a User Name. 
  5. Use the Password as an Authentication.
  6. The server doesn’t support encryption.

The Server Doesn’t Support Encryption

You may get a warning regarding the server not supporting encryption due to some security issues. This issue can leave the server communications more vulnerable to hacking attempts.

1. Change Settings

In the warning, you’ll see the Change Settings button. Click on it and do the following:

  1. Change the security connection to SSL/TLS.
  2. Change the authentication method to “Normal password.”
  3. Change the port to 993.
After changing the settings, save them and re-laun

After changing the settings, save them and re-launch Thunderbird.

2. Choose a Different Email Provider

If modifying the settings does not solve the issue, you can also choose a different email provider that will offer a more secure connection.

You’re Unable to Send or Receive Messages

Thunderbird might stop sending or receiving messages for several reasons. It could be an issue with the server settings, your antivirus program, or your internet service provider. Let’s check each case.

1. Check IMAP Settings

You need IMAP to receive messages. To check the IMAP settings:

  1. Click on the email account that experiences issues.
  2. Under Options click on Account Settings.
  3. Select Server Settings in the left-hand tab.

Make sure you’re using the 993 port, SSL/TLS connection security, and “Normal” password.

2. Check SMTP Settings

You need SMTP to send messages. To check SMTP settings:

  1. Go to Account Settings like in the previous step.
  2. Click “Outgoing server” in the left-hand tab.

Make sure you’re using the 587 port, “None” in connection security, and “Normal” password.

3. Whitelist Thunderbird in Your Antivirus Software

If your server settings are fine, it’s probably the case that your firewall or antivirus doesn’t trust the Thunderbird version or any new updates.

Whitelisting the email tool also fixes the issue for many users. In Windows Security:

  1. Navigate to Settings.
  2. Select Update & Security and choose Windows Security.
  3. Access the “Manage settings” option after clicking on “Virus & threat protection.”
  4. Go to the “Add an exclusion” option via “Add or remove exclusions” and select Thunderbird. 

For Windows Firewall:

  1. Type the word “firewall” in the Windows search box.
  2. Select the “Allow an app through the firewall” option.
  3. Click on the “Change settings” button.
  4. Add Thunderbird to the list after hitting the “Allow another app” button.

If you’re using another antivirus program, please consult with its Help section for specific guidelines. The process should be similar though.

4. Rollback Thunderbird

Thunderbird 78 and higher versions need enhanced TLS security standards. So, with Thunderbird email not working correctly, the primary reason may be that your service provider does not support the newer TLS network encryption protocols. Hence, users will be unable to send or receive emails.

The solution for this issue can lie in simply rolling Thunderbird back to an earlier version. You can find an earlier release here. To get to a previous version:

  1. In your current version, go to the menu > Preferences and scroll down to Updates
  2. Turn off automatic updates by switching your preference to “Check for updates, but let me choose whether to install them.”
Uninstall Thunderbird without deleting any profile
  1. Uninstall Thunderbird without deleting any profiles and databases.
  2. Download a version that came earlier than Thunderbird 78.
  3. Install the downloaded version.

Your accounts should appear in Thunderbird after launching. If you deleted Thunderbird together with the database files, simply log into your accounts again.

5. Contact Your Internet Service Provider (ISP)

On specific ports, such as port 25, few ISPs tend to block your outgoing emails. If you can’t send emails, then switching to another port is recommended.

You can also contact your ISP for any further help. For example, if you use Gmail, check the Google Dashboard for any status updates, in case it experiences downtime.

You’re Unable to Delete Messages

If you cannot delete messages in Thunderbird, it may be caused by a corrupted trash folder. Also, sometimes Thunderbird may freeze when deleting messages – in this case, try relaunching the app.   

How to fix

The simple solution is to create a new trash folder after deleting the old corrupted one. Follow these steps to resolve the issue:

  1. Access the troubleshooting information for the Profile Folder from the Help section of the menu button.
  2. Click on the Open Folder option from the Application Basics section.
  3. Now close the Thunderbird app.
  4. Go to your file manager and open the Mail (or ImapMail) folder per your affected account type (POP or IMAP).
  5. Remember to open the folder with an incoming mail server name like or
  6. Select the Trash.msf and Trash files and then delete them. These files may be named Deleted or Bin in some accounts.  
  7. As a final step, Restart the Thunderbird app on your system.

That’s it! The trash folder will be renewed, and you will be able to easily delete your mail messages.

Thunderbird Freezes or Works Slowly

Users may face Mozilla Thunderbird freezing, not responding, crashing, or hanging due to configurations or other systematic issues. These issues can be quickly resolved in the following ways.

1. Update Thunderbird

Quite often, an outdated Thunderbird version causes issues, and Thunderbird may freeze on Windows 10. First and foremost, users can fix the freezing or slow running issues by updating Thunderbird. Follow the steps listed below:

  1. Run the Thunderbird application.
  2. Visit the Help menu.
  3. Choose the About Thunderbird option.
  4. The software automatically checks for any updates after a window opens.
  5. Select Restart Thunderbird to update once updates are ready to install.
2. Try Running from Safe Mode
2. Try Running from Safe Mode

You can use Safe Mode to troubleshoot issues and reset settings. To launch it:

  1. Press the Alt (Option) key and click on the Thunderbird icon to launch it.
  2. If it’s already running, you can switch to Safe Mode by selecting “Restart with Add-ons disabled…” in the Help menu.
When the Safe Mode dialog appears, click on &ldquo
  1. When the Safe Mode dialog appears, click on “Continue in Safe Mode.”
3. Disable Add-ons
3. Disable Add-ons

You can also fix the issue by disabling the add-ons from Safe Mode. Do the same actions as in the previous step, but in the dialog, check “Disable all add-ons” and press the “Make Changes and Restart” button.

4. Reinstall Thunderbird

If your Thunderbird installation is corrupted, then Thunderbird issues may occur. No need to worry. This can be easily fixed in most cases by reinstalling the Thunderbird application.

Remember that specific registry entries or files can be left behind by applications despite uninstalling. Those files can cause some future issues, so it’s advised to remove them as you encounter them.

5. Check Email Configurations
  1. Go to the Tools menu and select the Account Settings option.
  2. You can also select Account Settings from the application menu.
  3. Once in the Account Settings, choose the Server Settings from the left pane.
  4. Ensure that you have correct Thunderbird login information in the right pane, and that should do the trick.

IMAP Server Error Message

Thunderbird IMAP problems usually occur due to the configuration of the IMAP server (such as Courier-IMAP), which may be configured to only allow a certain number of connections per IP address. 

1. Reduce the Number of Connections

An IMAP server error can be quickly resolved by reducing the number of connections. To do so:

  1. Select the Tools option from the menu and then choose Account Settings.
  2. Under the appropriate account, select the Server Settings.
  3. Click on the Advanced button.
  4. Once Configuration Dialog pops up, change the maximum number of server connections to cache value to three or less.
Update Thunderbird
Update Thunderbird

Upgrading your Thunderbird to a 68.3.0 version or higher should fix the error on its own.


Thunderbird’s muscles produced less fatigue toxins than the muscles of ordinary humans. He could exert himself at peak capacity for several hours before fatigue began to impair him. Superhuman strength and could lift approximately 2 tons under optimum conditions. His muscle tissue was three times as dense as that of a normal human being’s and was distributed in such a way as to give Thunderbird massive shoulders, arms, and thighs. His skin was several times as dense as that of a normal human being’s and included an additional layer of leathery epidermis. Hus lungs were oversized, and his respiratory system was developed in such a way as to allow him maximum wind and endurance with a minimum of oxygen intake. These features made Thunderbird a natural outdoor fighter and athlete. Also he was somewhat more resistant to physical injury than an ordinary human due to the density of his skin and muscle tissue. Not invulnerable, he was capable of withstanding impact forces and blunt trauma that would have severely crippled or killed an ordinary human with only mild to moderate discomfort. Thunderbird was also a very skilled tracker.