Export MBOX from Thunderbird to Microsoft 365 in Two Methods.

Let’s see how to convert MBOX from Thunderbird to Microsoft 365 account with the three methods. Of those, two methods are manual, and one is an automated tool.

So Office 365 works on the cloud and will be efficient in the future. as well as cost-effective. Even enterprise users or business users can use an Office 365 account. Every single user can use this Office 365 account. Because of his cloud-based features, it can be managed very easily.

Users of desktop email clients are the same. Users who found more ease in the Office 365 cloud email client have already shifted. This cloud functions in such a way that anyone can access their account from any location and any system. In this blog post, we are solving the problems of many users who are looking for a way to move their MBOX emails to Office 365.

The MBOX Files of Any Email Client.

  • Mutual email clients like Entourage, Apple Mail, The Bat, Mozilla Thunderbird, etc.
  • Download it from email clients like Gmail.
  • Users can create backup files from backupify, Mozbackup, etc.
  • Some old mailboxes with different extensions:.mbox,.mbox,.mbs, MBOX.
  • This process is valid till your MBOX file is in a healthy state. You can easily export MBOX files from Thunderbird to Office 365.
  • We will talk about the manual process first.

Import MBOX from Thunderbird to Microsoft 365 using free methods.

  1. Open Office 365 account in MBOX email client.
  2. After that, we will discuss the best third-party MBOX to Office 365 converter

# 1: Configure the Office 365 Mailbox in the MBOX Email Client.

We will use the IMAP account configuration setting as a free email client exchange.

Part 1:

  • Download and install the Mozilla Thunderbird email client from the official website.
  • Open Mozilla Thunderbird
  • Skip the process of creating a new account and opt for the option of using existing emails.
  • Now, enter your Office 365 credentials into the Mozilla Thunderbird account details.
  • Then click on “manually configure” and enter these settings:
  • Incoming: IMAP, server name –, port – 993, SSL – SSL/TLS, Oauth2 authentication, username – your O365 email id
    Outgoing: SMTP, server name –, port – 587, SSL – STARTTLS, Oauth2 authentication, username – your O365 email id
  • Hit the “Done” button on the right-hand side.

Part 2:

  • Now, use the ImportExportTools NG add-on to import MBOX files into Mozilla Thunderbird.
  • With the email client still open, press Alt.
  • Click on the Tools menu and choose Add-ons.
  • Use the search bar to search for ImportExportTools
  • When you click the +Add button, it adds the corresponding.
  • Now, reopen the email client.
  • Right-click on “Local Folders” >> ImportExportTools NG >> Import MBOX File
  • Hit the OK button and select the MBOX files. and click “Open.”
  • The file is added and the email client is opened to see emails.

Part 3:

  • Right-click on all of the MBOX emails (Ctrl+A).
  • Select “Copy to” your Office 365 account from the drop-down menu.
  • This will copy all of your MBOX from Thunderbird to Microsoft 365. Verify that all the files are present in your Microsoft 365 account using a browser.

The Drawback of Manual Methods

  • It requires the installation and configuration of two or more email clients.
  • Requires some tech skills to perform these steps.
  • It does not guarantee data integrity.
  • Steps are time-consuming, and if there are multiple MBOX files, they will become extremely complicated.

Third-party Software to Import MBOX Files into Office 365

If you are a busy person, that manual method is not your cup of tea. This is the reason we are suggesting a third-party solution in this blog post.

Features of MBOX to Office 365 Migration Tool

  • This software gives an option to import MBOX emails in bulk.
  • Impersonation allows you to upload files to multiple accounts at once.
  • A date-range filter is offered to migrate certain emails.
  • Maintaining folder hierarchy and structure.


In conclusion, well we elaborated the manual method in three parts for a better understanding of users and get the better result of importing MBOX from Thunderbird to Microsoft 365. On the other hand, the manual always comes with limitations so now it is your choice to select the methods. We also describe the tool method of the top-rated MBOX to Office 365 converter tool by experts. This software has a demo version, if want to know the working of the software then you can try the demo version.

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