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Written By Rohan Wiese
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Updated on July 18th, 2025
An MSG file is a single email message file created and saved by Microsoft Outlook. It stores data, like the message body, attachments, sender/receiver info, date, and more. These files are particular to Outlook’s environment.
But Thunderbird doesn’t support MSG files directly. That’s because Thunderbird is designed to read emails stored in formats like MBOX (for folders) or EML (for individual messages). As a result, when you try to open an MSG file directly in Thunderbird, nothing happens, or it appears corrupted. That’s why conversion is necessary. First, you need to convert MSG files to a Thunderbird-supported format, and then import them.
There are several real-world situations where importing MSG files into Thunderbird becomes essential:
Whatever the case, the goal is the same to access your MSG data in Thunderbird without losing content or formatting.
There are mainly two methods available:
Let’s navigate to each method in detail so you can pick the best option based on your needs.
This method is suitable if:
Follow the Steps below to Import MSG Files into Thunderbird
Now, you need to migrate Outlook messages to Thunderbird as EML:
Note: This method doesn’t support bulk conversion for thousands of emails and often struggles with attachments or metadata.
Although it’s free, the manual approach has several downsides:
Handling a large number of MSG files or working without Microsoft Outlook can make the manual import process time-consuming and unreliable. To avoid these limitations, using the Aryson MSG Converter Tool is highly effective. It preserves all essential email elements such as attachments, metadata, formatting, and folder structure. Additionally, it features a simple and intuitive interface, making it suitable for both technical and non-technical users. This tool eliminates the need for Outlook installation and streamlines the entire MSG to Thunderbird import process with ease.
Throughout this blog, we explored two reliable ways to import MSG files into Thunderbird. The manual method involves using Outlook and Thunderbird add-ons to convert MSG files into EML format, which can then be imported. While it’s a workable option for a few emails, it demands time and technical effort. For a faster and more efficient approach, above above-recommended automated solution is best to simplify the process. Depending on the number of files and available resources, choosing the right method ensures a smooth and hassle-free import experience.
Ans: Outlook is required if you’re using the manual method, as it helps open and export MSG files to EML. However, with Aryson MSG Converter Tool, you can convert MSG files to MBOX without installing Outlook.
Ans: Thunderbird supports both MBOX and EML formats. MBOX is ideal for importing complete mailboxes, while EML is suitable for individual emails.
Ans: Yes, if you use a reliable Aryson MSG Converter Tool, it will preserve all attachments, inline images, and formatting. Manual methods may not always retain everything, especially with large or complex emails.
About The Author:
Rohan Wiese is a Technical Writer at Aryson Technologies. He is an expert Email Forensic, Cloud Computing, and a passionate nerd with over 10 years of experience in technical content writing. He writes about Cloud Migration, Database Recovery, Email Backup, Windows, Mac, and Tech.
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