How to Fix Thunderbird Server Connection Was Reset

Thunderbird: Connection To Server Was Reset. A Complete Steps to Fix

Over the years, many users who use Thunderbird have reported the issue where Thunderbird says, “Connection to server was reset.” This has given many of you using Thunderbird a big headache. 

However, what are the causes of this issue? And how can we fix them? So, in this article, we try to find the cause of Thunderbird showing the connection to the server was reset message and propose a complete fix of this issue. 

What is Thunderbird? 

Thunderbird is one of the best free and open-source email clients software. It is used to store and manage your email accounts. If you have multiple email accounts and have difficulty juggling over them, using email clients like Thunderbird, you can instead set up each of these accounts in one place.  

Thunderbird helps organize your messy inbox from many different email providers and helps in giving out fast replies, maintaining your news and chat groups, and performing various other functions that work on multiple accounts with a similar set of procedures. It means you can add as many email accounts in Thunderbird and manage them effectively for free. 

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Why does Thunderbird show “Connection to server was reset.”

The error “Connection to server was reset” means that while the email client (Thunderbird) was still sending data, the server closed its connection to the client. It is mainly a server issue that needs to be fixed from the server side. However, there may be some potential reasons from your side (the client side) that may be causing this problem. 

Some of the potential causes of this issue on Thunderbird and why Thunderbird shows this error are:  

  1. Antivirus Mail Shield is blocking Thunderbird
    Most of the current antiviruses available have an advanced email protection feature. This is to prevent any malicious software from entering your system through your emails.
    However, this email protection module of your antivirus software (especially Avast and AVG) is known to conflict with Thunderbird making it display the connection to the server was reset error. To fix this issue, you can disable the email protection shield on your antivirus or uninstall and reinstall the antivirus on your system.
  1. A modified version of Thunderbird is being used. 
    You may not be using the original version of Thunderbird but a modified version of it. In such cases, Thunderbird will show the connection to the server was reset error.  
    It is best to use the original version, however for whatever reasons you may end up using the modified version, you should be aware that the Windows firewall will try and block some of its features. In such a case, you need to allow Thunderbird to communicate through the Windows Firewall. 
  1. A problem with your VPN or Proxy. 
    A problem with your VPN or proxy may be causing problems with your network, making Thunderbird give out the message saying that the connection to the server was reset. 
    As VPNs and proxies are known to hide your IP address and route your incoming traffic through various servers, your email client, like Thunderbird, will have trouble picking the right server to send emails. In such a scenario, you need to disable your VPN and proxy settings.  

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  1. Problem with Windows Firewall.  
    A problem with the Windows firewall might be causing the problem for Thunderbird. Sometimes even allowing Thunderbird access through the Windows Firewall might not do the trick. So, in such cases, you need to disable the Windows Firewall on your computer  
  1. Use of an old Thunderbird.
    If you have not updated your Thunderbird and are still using the old version, sometimes, you will get the error of the connection being reset.
    It is mainly due to your Thunderbird not having the patch files or other necessary software updates required to operate Thunderbird effectively. In such cases, the best option is simply to update your Thunderbird to its latest version. 
  1. Your Thunderbird network settings. 
    Sometimes, the issue of connection reset may be due to some in-built settings of Thunderbird. When you specifically send and receive emails through Gmail, or any other email provider, you may encounter the connection being reset. The issue also may be due to your IP settings on Thunderbird. 

How can you fix the “Connection to server was reset” issue on Thunderbird

To fix the “Connection to server was reset” error on Thunderbird, you can try and follow one or more of these methods. 

Turn off the advanced email shield on your antivirus (Avast or AVG).

If you find out that your antivirus software is the problem that is causing Thunderbird to show the connection reset error, follow these steps to disable the email protection shield from your antivirus.  

Disable mail shield from Avast 

  1. Open Avast on your computer.  
  2. Click on Settings from the left navigation plane. 
  3. Click on Protection from the list of options. 
  4. Click Core Shields on the right tab, and under Configure Shield Settings, select Mail Shields
  5. Uncheck the box saying Enable Mail Shield
  6. On the new menu, click on Stop permanently and click Ok
  7. This will enable the new settings with the mail protection shield disabled.  

Turn off email shield in AVG 

  1. Open AVG on your device. 
  2. Go to its settings and select Basic Protection
  3. Go to Email Shield and slide the green button to the left to disable it. 

This is a temporary solution as you have to turn off the email shield on AVG every time you restart your computer.

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Reinstall your antivirus software 

If you use a different antivirus suite than Avast or AVG, you can try and disable their email protection feature. If disabling the email protection does not work, you need to remove the antivirus from your system before reinstalling it. 

  1. First of all, uninstall the current antivirus on your system. 
  2. Go to Control panel > Program > Uninstall a program.
  3. Find the antivirus and uninstall it. 

Then, reinstall the antivirus and check to see if the connection reset error problem exists on Thunderbird or not. In many cases, this method works, and Thunderbird will stop giving out the connection reset messages. 

Disable the VPN  

Of the many individuals encountering this Thunderbird issue, a lot of them solved it by simply disabling their VPN. So, if you also have a VPN service on your computer, you can disable it and try to see whether the connection reset problem on Thunderbird persists or not. 

As VPNs are known to interfere with Thunderbird and its processes, it would be a good idea to disable them. However, if the issue persists, you should understand that the problem is not with the VPN. In such a case, you can try and opt for any of the other methods to fix this solution. 

Allow Thunderbird access through the Windows Firewall

  1. Go to Control Panel > System and Security. 
  2. Click on Windows Firewall > Allow and app or feature through Windows Firewall.
  1. Go to Change Settings. 
  1. Search for Thunderbird from the list of apps. 
  2. If Thunderbird is not found, click on Allow another app
  1. Browse for the file path of Thunderbird, and click on Add
  2. After adding Thunderbird, tick on checkboxes of both Private and Public and click on Ok

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Turn off your Windows Firewall  

  1. Go to Control Panel > System and Security. 
  2. Click on Windows Firewall. 
  1. Next, click “Turn on Windows Firewall On and Off.
  2. Tick the checkbox saying “Turn off Windows Firewall” on both Public and Private Network Settings on the resulting window. 

Edit the Network DNS Settings on Thunderbird

  1. Go to the three lines on the top right and click on options
  1. Scroll to the bottom and click on Config Editor.
  1. A dialog box will open, warning you of the risk of changing the settings. 
  2. Click on I accept the risks. 
  1. Search for IP on the resulting window by typing “ipv” on the search bar.  
  2. Turn the “network.dns.disableIPV6” value to true. Or, 
  1. On the “network.dns.IPV4OnlyDomains” add the string “

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Update your Thunderbird to the latest version

  1. Open Thunderbird.
  2. Click on three lines on the top right corner, and select Help.
  1. Click on About Thunderbird
  1. There, you will see the current version of your Thunderbird as well as available updates. 

At the end

The connection to a server reset problem with Thunderbird is a major issue giving you headaches. It is especially severe when you have multiple email accounts and need to reply to your emails within a set deadline. However, now, with the methods mentioned above, you should be able to fix this problem and go on with managing your emails effectively. However, if you disagree with some of the methods mentioned above or have some queries or confusion, you can put them in the comment section below. We will be sure to respond to your query as soon as we can. 

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