How Fix Thunderbird SMTP Error – Messages Cannot Send

“Yesterday, while I was sending a mail from my Thunderbird, it prompts an error message saying that ‘Try again’. After that, I called my ISP and they said that my account is all fine and actively working. I am receiving emails but why outgoing (SMTP) service is disabled. I do not have any idea that how to resolve this issue please someone suggest me that what is the cause of this error and how can I determine it.”

If you are the one who is facing the same issue then, you are certainly on the right page. Here we will discuss all the probable causes behind this error and the ways to resolve it. Well, before going for the solution section, users must have an idea about this Thunderbird sending of message failed error. So let us begin with a brief introduction of this email sending issue.

Cannot Send Emails by Thunderbird

Sometimes it ensues: users simply cannot send emails. After launching Thunderbird, composing a message, and sending it returns an error. Why?

Well, if a user is unable to send any email via Thunderbird then, the dilemma is very likely related to the Thunderbird SMTP server error. The SMTP server administers the entire email delivery procedure. The Thunderbird mail sending error occurs while traveling and linking with a different ISP from normal. It is so because the ISP blocks the outgoing ports as a protector against the connections that are used to send spam. This error can occur in many statements, some of them are mentioned in down screenshot:

Methods to Fix Mozilla Thunderbird Cannot Send Messages Error

In this section, we will discuss some ways through which users will surely be able to send emails again via Thunderbird

Extra Info: 

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Fix 1: Examine the SMTP Email Outgoing Settings

The most probable cause of this error is disturbed SMTP server settings. Therefore, first, we have to inspect the outgoing server settings. Here is how to do this:

• Launch Mozilla Thunderbird and click on the Tools tab
• Select the Account Settings option from the opened menu list
• Click on the Outgoing Server (SMTP) option
• Then, check the SMTP server settings are correct for the configured email account or not
• Additionally, ensure the email provider’s website and seek for Mail Settings >> SMTP

Inspect the Correct SMTP Settings is Using or not

Users also have to check that, which SMTP Settings they are using. To do this follow the down mentioned steps sequentially:

• Open Thunderbird and click on the Tools option
• Select Account Settings and select the account name that is having an email sending problem
• Next, make sure the correct SMTP server is using or not for the given email address
• For example, emails cannot be sent by any xyz@gmail.com through Yahoo SMTP

Fix 2: Check for Email Blocking Services

Sometimes installed antivirus or firewall applications block the outgoing email service of Thunderbird. Thus, it is a must to check that what is blocking emails from sending.

• For this try to send an email without disabling any antivirus or firewall software and then send the email after disabling them.
• Additionally, many ISPs block the outgoing email from port 25. So, change the port number 465 or 587 after asking the service provider.

Fix 3: Delete Password from SMTP

This email sending issue can be resolved via deleting and reconfiguring the email account. Here is how to do this:

• Update Mozilla Thunderbird application to the latest version
• Then, try to send an email for checking that the problem still persists or not
• If it does, select Tools >> Options
• From the Options wizard, click on Security >> Password
• Now, delete the SMTP password and configure the email account again. Then, try to send an email again and this can resolve the Thunderbird email not sending issue.

Reset the SMTP Password

Resetting the SMTP password also can determine this issue. Here is how to reset the SMTP password:

• Launch Thunderbird and go to the ISP site
• Now, click on Reset Password
• Change the password and then, add this new password to Thunderbird

The above-given solution will help you to solve the Thunderbird SMTP error and remove Thunderbird sending of message failed error.

The Final Verdict

The SMTP issues can occur at any time and they can affect the working of a Thunderbird application. Hence, it is significant to rectify the Messages Cannot Send by the Mozilla Thunderbird problem. Many solutions have been described in this blog to resolve Thunderbird mail sending errors. Users can opt for any of them as per their requirements.