5 Ways to Fix Thunderbird SMTP Error

Updated On - March 30, 2024 by Prakriti Malsuni | Reading Time: 6 minutes

In the emailing world,  Thunderbird is not a new name but along with its many advantages, it also encounters some errors. E.g., SMTP error.  Hence, a search to fix Thunderbird SMTP error is common on the internet.

You will get detailed information here if you also want to eliminate this Thunderbird SMTP error. This write-up will cover this issue’s dimensions and provide a solution to fix Thunderbird SMTP error. Read the blog till the end and get complete information concerning this issue.

What is an SMTP Error in Thunderbird and How to Resolve It?

In many scenarios, users face an error when they send an email. While sending an email, they encounter that the emails are not delivering. If it happens once in a blue moon, it is not an issue, but frequently encountering this error is a big problem as it directly affects professional life. It restricts users from sending an email.

As there may be many reasons behind the SMTP error, we must cross-check each to fix the SMTP Thunderbird issue.

4 Simple Workarounds to Fix Thunderbird SMTP Error

 1: Update Thunderbird

The first and most obvious task to resolve the Thunderbird SMTP error is updating the Thunderbird. Due to the TLS network encryption protocol, security standards are now very high, and we must comply. Hence, updating the latest version and configuring it again is recommended.

 2: Cross-Check IMAP and SMTP Settings

The most crucial step is checking for the IMAP and SMTP Settings. Follow the below-given step to check settings:

  • Firstly, log in to the Thunderbird application.
  • Now, Tools >> Account Settings.SMTP Settings
  • A new window will open where you select the Outgoing Server (SMTP) from the left pane.
  • Cross-check that the SMTP settings are the same as the Mozilla Thunderbird prescribes. Moreover, confirm it at support.mozilla.org.
  • If you find any mismatch, click the Edit button and edit the settings as convenient.
  • Finally, cross-check whether the problem is resolved by sending a test email.

3. Check If the Outgoing Email Server is Blocked

We all know that firewalls, antivirus, and sometimes internet service providers also cause the blocking. To cross-check it, disable the Firewall and Antivirus for some time and cross-check by sending an email. Also, internet service providers block many ports in many scenarios, and sometimes, unknowingly, outgoing email ports sending emails get blocked.

 4: Try Reset SMTP Password

If you are still trying to fix the Thunderbird SMTP error after doing all the above workarounds, you can reset the password and check if it works. Follow the steps to change the SMTP password.

  • In the Thunderbird account, go to Tools.SMTP Thunderbird Password
  • Now click on Options.
  • Click on Security >> Passwords.SMTP Password Change
  • Finally, delete the old SMTP Password and reset the new one.

  What If All the Above-Given Workarounds Failed to fix Thunderbird SMTP Error?

If, even after doing all the workarounds explained above, the problem persists, then changing the email client becomes the last option. However, migrating from the current email client is challenging, but circumstances initiate the same. Practically, after having a bad experience with struggling to fix Thunderbird SMTP error, users search for the better option. Market trends show that Outlook is the popular email client, and there is a clear tilt toward Outlook, a Microsoft product.

Solution 5. Move from Thunderbird to Outlook

If you have decided to move from Thunderbird to Outlook, then converting all current Thunderbird data to Outlook is the priority. We must know that Thunderbird saves email data in the MBOX file format, and Outlook has OST and PST file formats with unique characteristics. Users can add PST files to Outlook and access their email data on the Outlook email client. MBOX to PST Converter, developed by Regain Software, is a one-stop solution for this conversion. This software comes with multiple user-centric features that offer an efficient but effortless conversion process. Some of the highlighted features of this utility are:

  • Regain MBOX to PST can easily convert multiple MBOX files without any size limitations.
  • Furthermore, along with the PST file format, it offers MSG, PDF, EML, and HTML-like file formats to save the data.
  • This utility properly keeps the originality of the data and meta properties/ attributes intact; there are no changes in the folder hierarchy.
  • Similarly, it has a very user-friendly GUI, making it easy to run for non-technical users.
  • Another key point, if you have large-sized MBOX files, you can easily set a size limit for the resultant PST files. Oversized PST files are prone to corruption; hence, keeping them in limit is an intelligent decision.
  • This advanced utility is compatible with all the Outlook and Windows Operating System versions.

Free Download100% Secure Buy NowPrice: $29

Easy Steps to Convert MBOX to PST File Format:

  • Firstly, download and install the Regain MBOX to PST Converter. An Alternate Way to fix Thunderbird SMTP error
  • Browse and select MBOX files.
  • Now, you can have a preview of the items within the folder. Add MBOX Files to Convert
  • Here, provide the destination path to save your resultant PST files. Also, select Save to PST; you can choose any other file format per the requirement. You can also use Split PST by option for PST files to set a size for the resultant PST file. Fix Thunderbird SMTP Error
  • As the process completes, you will get a message that “ Saving process has been completed”. Fixes SMTP Thunderbird Error

Over to You!

You can try the above methods if you are fed up with not delivering email issues and want to fix Thunderbird SMTP error. If these manual workarounds don’t come in handy, then changing the email client remains the last option and is your decision. A professional tool is available in this blog to export Thunderbird to Outlook. Users can simply download and try the demo version.

Frequently Asked Questions

Q1. Suppose I fail to fix the Thunderbird SMTP error and want to switch Thunderbird to Outlook. Will I get complete email data in the PST file format using Regain’s software?

Ans. Using the Regain MBOX to PST Converter, You can quickly convert all your email data with the same hierarchy. You can simply switch from Thunderbird to Outlook.

Q2. Can I get technical assistance with Regain’s MBOX converter utility if I struggle to fix Thunderbird SMTP error?

Ans. Regain’s technical support team is round the clock and available to assist you. Contact us if you want to convert MBOX to PST and need assistance. Contact us through live chat/ by emailing support@regainsoftware.com or call us at the contact number on the Contact Us page.

Q3. I want to convert some MBOX files to PST format to get assured before purchasing; is there any chance?

Ans. Yes, you can get assured before purchasing the license. Download the free demo version and convert some initial MBOX file items for free. However, the trial version allows the processing of 30 items per folder. After getting satisfied, you can simply upgrade to the full version.

Q4. Can I manage the newly created PST file size using Regain MBOX to PST Converter?

Ans. Regain MBOX to PST Converter offers an option to split the resultant PST file size. Similarly, you just have to set the size to create PST files, and the software will split it upon reaching the size.


Author: Prakriti Malsuni

Hi, I am Prakriti Malsuni (Pooja), a dedicated technology enthusiast and writer, focusing on the realm of email and its related technologies. Working closely with Regain Software, I delve into the intricate aspects of email protocols, email clients, servers, and other related dimensions. Through insightful articles, I aim to demystify complex concepts into understandable write-ups for a wide audience.

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