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Prime Solutions to Resolve “Cannot Send Messages using Thunderbird” Query

Published By Mohit Jha
Tej Pratap Shukla
Approved By Tej Pratap Shukla
Published On December 31st, 2021
Reading Time 5 Minutes Reading

Are you a Thunderbird user who is facing some problems regarding sending emails? Stay tuned as we will provide you with some effective approaches to resolve the common user query: cannot send messages using Thunderbird.

user queries

First, understand this with a related user query.

“Hello to all! I have been using Thunderbird as my email client for many years now. Recently, I updated it and installed the latest version. Since then, I am unable to send messages using Thunderbird. I have checked my SMTP settings and it seems that everything is in order. I do not have a clue why this issue is happening to me. I talked with some of my friends who are using the same Thunderbird version. They confirmed not having any such issues. Can you offer me any solution to this annoying problem?

Among many other Thunderbird issues faced commonly by its users, failing to send email is a major one. That is why we see a large number of queries where users complain that they cannot send messages using Thunderbird. This is undoubtedly a major problem that needs to be fixed without wasting time. For this blog, we have chosen to discuss multiple methods that can be used to resolve this Thunderbird problem. Continue reading this post to know more.

What to Do If You Cannot Send Messages using Thunderbird

Mozilla suggests using these methods if you are unable to send messages.

I. Outgoing Email Settings Verification of SMTP

  1. Click on the Tools button from the Thunderbird menu bar and click on Account Settings. Or you may click on Thunderbird Menu button, select Options and go to Account Settings.
  2. Choose Outgoing Server (SMTP) located at the bottom of the left panel.
  3. Verify if the settings is correct for the configured email account.
smtp settings

You can check them on on the email settings article for the particular email service provider like Gmail, Hotmail, Yahoo, etc. In case no such article is available, check the website of email client for Mail SMTP Settings.

II. Check If the Correct SMTP Server is in Use

  1. Click on Tools >> Account Settings to access the Account Settings window.
  2. Select the account name that is having the issue. You need to confirm whether you are using the correct SMTP server for your email address.

In most cases, you cannot send messages using Thunderbird when you try to send emails from one account using the service of another account provider, like you cannot send email from using the SMTP server of Gmail.

III. Check If Anything is Stopping Emails from Being Sent

Users also need to verify whether the Windows firewall, anti-virus program or ISP is responsible for this problem.

  • Turn off your system firewall as well as anti-virus program temporarily and send a test message to see if Thunderbird can send the email. If yes, then enable firewall and anti-virus again and send another test mail to point out where the problem lies.
  • Contact your Internet Service Provider to know if they are blocking the outgoing email port. Some ISPs do not allow outgoing email on port 25, so you can try switching to port 587 or 465.

Note: Anti-virus program or firewall often blocks Thunderbird outgoing email after a Thunderbird update as they do not recognize the updated version. To resolve this, remove Thunderbird from the list of trusted applications and add it again manually when prompted.

IV. SMTP Password Delete

Users can also try deleting their password for SMTP. But keep this method for the last. If Thunderbird is not sending messages after an update, do not perform this step as there might be no problem with the SMTP password.

V. SMTP Password Reset

As the last resort, you can also try changing the SMTP password. For that, visit the support password of ISP and fill the ‘reset email password’ form. Go for this solution to fix Thunderbird SMTP error only if nothing else works.

Another Thunderbird Query

Hello, for the past few days my Thunderbird account has been behaving very abruptly. I am unable to send any message whatsoever. No internet solution works. SO I decided to move to Outlook platform. Provide me something by which I can move all my data to Microsoft Outlook. Thank you!”

There have been cases when common problems such as cannot send messages using Thunderbird frustrates users to the limit. Either personally or professionally they seek better email platforms such as MS Outlook. For this purpose, consider using MBOX Converter software. You can perform migration to Outlook PST as well as save emails in EML, HTML, MSG, NSF format. Try now for 100% guaranteed conversion in the least possible time.


There can be multiple reasons for which users cannot send messages using Thunderbird. This problem is a serious one and users need an immediate solution to this issue. Therefore, we have included several techniques that can be implemented in such cases. It is expected that users will be able to fix the issue using one of these methods. If these methods fail to fix your issue, contact Mozilla with a new support request where you have to include information about Thunderbird version, email client, ISP name, firewall version, OS name and version, anti-virus name and version.


By Mohit Jha

Mohit is a Microsoft-certified expert who has assisted thousands of clients with Outlook & Microsoft Office 365 issues. He enjoys writing on email clients as well as data migration. He is always excited about giving troubled readers the most up-to-date knowledge, explanation, and refinements.