How to Import MSG Files into Thunderbird With All Attachments

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  • Updated on September 18th, 2023

Summary: This guide helps you open MSG files in Thunderbird, either by doing it yourself or using a special tool called the MSG Converter Tool. But before we get into that, let’s talk a bit about what MSG and Thunderbird are. Afterward, we’ll go over why someone might want to convert MSG files to work with Thunderbird. First, let’s tackle the user’s question about how to import MSG files into Thunderbird.

MSG vs Thunderbird

MSG is a proprietary file format created by Microsoft for storing email messages. It is a binary format, which means that it is not human-readable. MSG files can only be opened by email clients that support the MSG format, such as Microsoft Outlook.

Mozilla created the open-source email client called Thunderbird. It supports a wide variety of email protocols, including IMAP, POP3, and SMTP. Thunderbird can also import and export email messages in a variety of formats, including MSG.

Let’s discuss the features of the MSG and Thunderbird applications:

PurposeStores email messagesStores email messages, manages calendars, tasks, and contacts
CompatibilityCompatible with email clients that can read the MSG file formatCompatible with a wider range of devices, email protocols and file formats
SecurityNot as secure as Thunderbird messagesMessages are encrypted
FormattingSupports a limited range of formatting optionsSupports a wider range of formatting options
SizeTypically smaller than Thunderbird messagesMessages can be larger due to attachments

What are the reasons behind the MSG to Thunderbird Conversion?

Here are the reasons why users are converting their MSG files into Thunderbird applications:

  • Thunderbird’s features: Thunderbird is a free and open-source email client that offers a number of features that are not available in Outlook, such as IMAP support, multiple account support, and add-on support.
  • Move to a different email client: If you are switching from Outlook to Thunderbird, you will need to convert your MSG files so that you can import them into Thunderbird.
  • Avoid compatibility issues: MSG files are a proprietary format that is not supported by all email clients. Converting them to Thunderbird’s native MBOX format will ensure that they can be opened and read by any email client that supports MBOX.
  • Save space: MSG files can be large, especially if they contain a lot of attachments. Converting them to Thunderbird’s MBOX format can reduce the file size, which can save space on your hard drive.

Now, let’s begin with the best solutions to import MSG files into Thunderbird with attachments.

Best Techniques to Import MSG Files into Thunderbird: A Step-by-Step Guide

Now, we’ll talk about the two best ways to transfer MSG files into your Thunderbird account.

  • How to Transfer MSG Files to Thunderbird Manually?
  • Direct Method to Export MSG Files into a Thunderbird Account?

Technique 1: How to Transfer MSG Files to Thunderbird Manually?

We’ll break this process into two simple steps. First, we’ll convert the MSG file into EML format. Then, we’ll import the EML files into Thunderbird. Let’s walk through these steps to transfer MSG to Thunderbird.

Step 1: Convert MSG to EML Format

Thunderbird can read EML files, so you’ll need to convert MSG to EML format. There are several ways to do this, but here’s one method using Microsoft Outlook:

  1. Open Microsoft Outlook.
  2. Locate and select the MSG file you want to convert.
  3. Drag and drop the MSG file into a folder on your computer. This will create an EML file with the same name as the original MSG file.
  4. Repeat this process for each MSG file you want to transfer.
Step 2: Import EML Files into Thunderbird

Now, that you have your MSG files converted to EML format, you can import them into Thunderbird:

  1. Open Mozilla Thunderbird.
  2. Select “Import” under “Tools” from the menu.
  3. In the Import Wizard window, select “Mail” and click “Next.”
  4. Choose “Import a directory” and click “Next.”
  5. Click “Select Folder” and browse to the folder where you saved your EML files. Select the folder and click “OK.”
  6. Thunderbird will start importing the EML files. Once the procedure is finished, click “Finish.”

By following the above steps, you can easily import MSG files into Thunderbird with or without attachments. Now, let’s discuss some limitations that you can face while using the manual method.

What are the limitations of the Manual technique?

It has some limitations that can create difficulty while using the manual approach. Let’s discuss:

  • This method only works for MSG files that do not have any attachments. If the MSG file has attachments, they will be lost during the conversion.
  • This method can be time-consuming if you have a large number of MSG files to transfer.

If you have a large number of MSG files with attachments and want to avoid the limitations of the manual method, you can use the MSG Converter MSG to Thunderbird converter tool. Step-by-step instructions are provided below.

Technique 2: Direct Method to Export MSG Files into a Thunderbird Account?

The MSG Converter is the best solution to import MSG files into Thunderbird. It has a simple GUI: therefore, non-technical users can use this application easily without any effort. This software can transfer any size of MSG files to Thunderbird. You can download a free demo version of the MSG tool that can transfer only 50 items per folder. Let’s move on to the step-by-step instructions for the MSG to Thunderbird conversion.

Steps to Migrate MSG to Thunderbird:

  1. Download & install MSG Converter.
  2. Then, choose the MSG files using the Select Files/Select Folder button.
  3. Next, Preview and select the files from the tree-structure list.
  4. From the drop-down menu, select Thunderbird.
  5. Now, Sign-In your Thunderbird account with your username and app password.
  6. Finally, choose the feature that you want, then click on the convert button.


As we mentioned above, there are two good ways to move MSG files to Thunderbird. The manual way is okay, but it has some limits. It cannot manage a large amount of data at once. On the other hand, the professional method is a direct and straightforward way to bring your MSG files into Thunderbird. You may decide which one best suits your requirements.

Frequently Asked Questions:

Q1. How do I convert MSG files into Thunderbird on Mac?

1. Download the MSG Converter.
2. Select files/folders.
3. Preview and choose files.
4. Pick “Thunderbird” from the dropdown list.
5. Sign in with an email and app password.
6. Select features and click “Convert” to migrate.

Q2. Can I export multiple MSG files to Thunderbird?

1. Download and run the MSG Converter.
2. Click “Select Files/Folders” to choose your files.
3. Preview and select the files you want.
4. Choose “Thunderbird” from the dropdown.
5. Enter your Email Address & App Password, then click “Sign In.”
6. Select features and click “Convert” to migrate.

About The Author:

As a lead technical writer, I know the technical problems faced by office and professional users. So, I decided to share all my technical knowledge through this blog. I love helping you with tough challenges when dealing with technical issues.

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