Resolve Connection to Server Timeout Error in Thunderbird

When sending or receiving an email in Thunderbird, it is a common error “Connection to server timed out” that troubles users at times. In that case, the server might take too long to respond to a request from your system. It also happens when users send or receive large emails or email having large sized attachment. As result, users are unable to send or receive emails because the server is not capable enough to answer the requests. While downloading email to Thunderbird, the active connection to Thunderbird fails. Now the users who want to continue using the email provider are having the Thunderbird “Connection to server timed out” error popping on their screen each time when they try to access the mail services in Thunderbird.

The error could be displayed with the following information:-

Send Message Error
Sending of the message failed.
The message could not be sent because the connection to Outgoing server (SMTP) timed out. Try again.

The message could not be sent because the connection to Outgoing server (SMTP) timed out. Try again or contact your network administrator.

You may receive that type of error, where the email fails to send because the server has taken too long time to respond to the sending request and the server time is out. So in this article, you will get information about what are the causes of this error and how you can fix this error permanently.

What cause the Connection to Server Timeout Error in Thunderbird?

Here are some common causes that may be reason behind the creation of this Thunderbird error:-

  • Incorrect SMTP port settings during the configuration
  • Program or Software like Windows Firewall, Antivirus etc. clashing with Thunderbird and blocking the emails
  • SSL or TLS Server setting is not configured properly
  • Server timeout is set at low value in setting
  • Spam detected by Internet Service Provider on Port 25

How to fix Connection to Server Timeout Error in Thunderbird?

After knowing the causes for getting the Connection to Server Timeout Error in Thunderbird, now we will know how these errors can be solved by following solution:-

Solution 1- Turn off Windows Firewall Antivirus

The Connection to Server Timeout Error in Thunderbird may cause due to blocking mail by third party software like antivirus or Windows Firewall. Antivirus or Windows Firewall does not allow transferring mail in your system, and then you need to disable the third party software like Antivirus or Windows Firewall which is responsible for the issue. To turn off these programs or software please go through following steps-

  1. Go to Control Panel on your system.
  2. Search Windows Firewall on Control Panel and go to Windows Firewall.
  3. After that go to Turn Windows Firewall on or off option.
  4. Now select the Turn off Windows Firewall for your network and then click on OK.

After disabling window firewall, please check if emails can be sent and received via the Thunderbird.

Solution 2- Check the outgoing server (SMTP) settings

Please check and correct the account configuration settings of the Outgoing Server (SMTP) in your Thunderbird email client by following steps-

  1. Open your Thunderbird email client application.
  2. Tap on Tools > Accounts.
  3. After that, click on the Outgoing Server (SMTP) tab.
  4. Now check the details like user name, Port, Connection Security Settings, Secure Authentication, etc.
  5. Click the Edit option to change any setting which you know is incorrect currently. Check that Connection Security Settings for SMTP are set to StartTLS.
  6. Restart the Thunderbird email client and try sending emails.
Solution 3- Increase the timeout value of the server

When a server takes too long time to respond to a request from your system, it happens when any user sends large emails or email having large-sized attachment. Then large-sized attachment takes too long time to deliver as the time set in server setting has reached its limit. So this error can be fix using increase the timeout value of the server. Please go through following steps-

  1. Open your Thunderbird email client application on your system.
  2. Navigate to Tools > Options > Advanced > General > Config Editor option.
  3. Go to the search file section and type mailnews.tcptimeout and press Enter.
  4. Right-click on mailnews.tcptimeout and then select the Modify option from the drop-down list.
  5. Now edit the value of time with larger no and save it.
  6. At last, restart the Thunderbird email client. Try sending emails with large size attachment for checking that server timed out error is fixed.

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Final words

It’s very irritating when we want to send any urgent email but error comes out as Connection to Server Timeout Error in Thunderbird email client. In this article, we have discussed 3 ways to fix the error. Hope your problem will get resolved using the above detailed solutions.

About Barrett Clay

Barrett is passionate about technology and an admirer who believes in offering instant computing solutions to everyone. He solves personal and business technical issues related to IT products, applications, IT environments, platforms, technologies, etc., through well-documented blogs and articles, informative, authentic and descriptive content. He participates in technical content development, content publishing and marketing.


  1. In business communication long emails are a common thing to sending or receiving, in this situation server took much time because of long size emails. And connection to server timed out error occur in Thunderbird. And after looking many methods I finally solved this error with above method.

  2. I also faced this error and due to this connection to server abrupt in Thunderbird. In whole process of solving this error I used these tips and successfully overcome.

  3. It happened many times when I am sending large emails from Thunderbird email client then this error “connection to server timed out error” displayed. I tackle this error with this solution. This solution means a lot to me.

  4. After many searches in the internet, I get this solution to eliminate connection server timed out error in Thunderbird. With the help of this blog, I am able to detect and solved the server timeout error. Thanks to the team, appreciate a lot.

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