Looking to export Office 365 to MBOX format but can’t seem to find a way around the problem. Don’t worry we have prepared this writeup to give you multiple approaches from ThunderBird to Gmail.
In case you are an admin looking to transform organization-wide M365 data to MBOX we have a solution for that as well.
Let us start by decyphering the MBOX family it will help us to pick out the best option out of all the available ones.
MBOX Types and Which One is Best to Export Office 365 Data?
| Feature | MBOXO | MBOXRD | MBOXCL | MBOXCL2 |
| Message Separator | “From ” line at the start of each message | “From ” line at the start of each message | “Content-Length:” header | “Content-Length:” header |
| “From ” Line Handling | Prepends “>” to any “From ” line | Prepends “>” to “From ” lines and strips on read | Prepends “>” to “From ” lines | Does not modify “From ” lines |
| Content-Length Header | Not used | Not used | Used to indicate message length | Used to indicate message length |
| Primary Use | Original UNIX format | Improved version to handle “From ” lines | Proprietary use in some systems | Proprietary use in some systems |
| Compatibility | Moderate due to ambiguity issues | High due to reversible quoting | Low, requires specific reader support | Low, requires specific reader support |
| Escaping Mechanism | Adds “>” to “From ” lines | Adds “>” to “From ” lines and removes on read | Adds “>” to “From ” lines | None |
| Corruption Rate | High, irreversible corruption is possible | Low, reversible quoting reduces corruption | Moderate, relies on accurate content-length | Low, no “From ” quoting used |
| Data Storage Capacity | Basic | Standard | Standard | More than CL |
| Use Case Acceptability | Moderate | High | Low | Low |
| Availability | Low | High | Low | Low |
| Overall Rating | ⭐⭐ | ⭐⭐⭐⭐⭐ | ⭐⭐⭐ | ⭐⭐⭐ |
Want to Export Office 365 to MBOX Manually? Use Thunderbird, Client
Step 1. Get a copy of Thunderbird from the official website and install it.
Step 2. Configure Microsoft 365 in Thunderbird
- Open Thunderbird.
- File > New > Email Account
- Enter Account Details:
- Name.
- Email ID.
- Password.
- You can toggle Remember password if desired.
- Click Continue.
- Authenticate with Microsoft 365:
- A Microsoft sign-in window will appear.
- Type your password.
- Complete the multi-factor authentication (MFA).
- Configure Server Settings:
- Thunderbird can automatically detect the server settings. Press Done.
- See if it matches the following:
- Incoming Server:
- Protocol: IMAP
- Hostname: outlook.office365.com
- Port: 993
- Connection Security: SSL/TLS
- Authentication Method: OAuth2
- Username: Your full email address
- Outgoing Server (SMTP):
- Hostname: smtp.office365.com
- Port: 587
- Connection Security: STARTTLS
- Authentication Method: OAuth2
- Username: Your full email address
- Incoming Server:
- Click Finish to finalize the account setup.
- Thunderbird can automatically detect the server settings. Press Done.
Step 3. Install ImportExportTools NG Add-on
- To export emails to an MBOX file, you’ll need the ImportExportTools NG add-on:
- Click on the Menu icon (three horizontal lines) in the top-right corner.
- Open Add-ons and Themes.
- In the Add-ons Manager, use the search bar to find “ImportExportTools NG”.
- Click on the Add to Thunderbird button next to the ImportExportTools NG listing.
- Follow the on-screen instructions and refresh Thunderbird.
Step 4. Export M365 to MBOX
- In Thunderbird’s folder pane, right-click on the email folder you wish to export (e.g., Inbox).
- Hover over the ImportExportTools NG option in the context menu.
- Select Folder export (mbox) > As mbox File. (You can choose other Export options like exporting with or without subdirectories based on your needs).
- A pop-up may appear to close it by clicking OK.
- Pick the folder (or create a new one) on your computer to keep these MBOX files.
- Thunderbird will start and complete the export on its own.
Add Your Office 365 Account in Google’s Gmail then Use the Google Takeout
You can either add your Office 365 Account or forward all the emails. Sometimes admins may disable email forwarding to external domains. So ask your admin to temporarily loosen the restrictions.
Other than that refer to the table below to get an idea about the upper ceiling of email forwarding from a M365 account.
| Category | Limit |
| Maximum Forwarding Addresses | 10 |
| Maximum Recipients per Forwarded Message | 500 |
| Forwarding Retention (Auto-Forwarding) | 90 days |
| Forwarding Rate Limit | 3,600 messages per hour |
| Size Limit per Message | 150 MB (including attachments) |
You can send any number of emails provided that you stay under these limits and don’t have any admin-level restrictions.
For security reasons, you can’t add an M365 account to Gmail directly
Check out the Microsoft Server settings to enable this.
Click on the settings cog > See all settings > Accounts and Import.
There you can use the “Import mail and contacts:” or “Check mail from other accounts:” option to set up your Office 365 account. Use the on-screen instructions to complete the setup.
After this Use Takeout Service
- Go to Google Takeout and sign in with your Google account.
- Click on Deselect all to uncheck all the data categories.
- Scroll down to Mail and check the box. Click on All mail data included to customize the labels (folders) you want to export, ensuring the emails from your Office 365 account are selected.
- Then, click Next Step.
- Choose the delivery method (e.g., Send a download link via email).
- Select MBOX as the file type.
- Then, click Create Export.
- Google prepares the MBOX file, which might take some time.
- Once the export is ready, you’ll receive an email with a download link.
- It will be a Zip file so extract it and download the MBOX File.
Why are the Manual Options Problematic for Organizations?
First of all, both methods are for a single-user account. Is very difficult for the admins to coordinate so many different users and check whether each of them has done all the steps in the right order.
A lot of time might be wasted in troubleshooting these manual multi-tier approaches across so many accounts.
The email forwarding has built-in limits, and adding the email account is quite a complex process.
Not to mention the MBOX files will be present in the user’s own machine rather than in a single organization-wide repository.
If users choose one method over the other admins may have to deal with different MBOX subtypes which brings even more challenges.
All these reasons push us towards a solution that can be deployed on a single workstation but can gather and pull data out of every Office 365 account and put them in the desired file type. You need not search anywhere else for such a solution as we have one right here
How to Export Office 365 to MBOX via A Dedicated Tool?
The SysTools Office 365 Export Tool can get the job done in no time. Moreover, w ith its intuitive user-centric design anyone with minimal technical know-how can use and operate the tool with ease.
Admins get access to a wide range of filters with which they can select the time range, the users, and the order of those users for the export operation.
Also Read: Steps to Save Outlook 365 Email as MSG File Format
Moreover, all this is packaged in a GUI-based environment. To use the tool follow these steps:
Step 1. Install and set up the tool, launch it, and select Office 365 as the source and MBOX as the output.
Step 2. Then, go to the Workload section and mark the checkbox next to the available workload. If you want you can enable the Date filter option and add a specific time range.
Step 3. On the Source Screen, you need to type the Admin email and App ID then Validate these values.
Step 4. Inside the Destination screen specify the appropriate file path to keep the extracted MBOX data in.
Step 5. Then, use any one of the available matching options out of Fetch Users, Import CSV, or Download Template to bring in your User List.
Step 6. Finally, in the Preview Screen, you can see the user list make selections apply priority, validate, and start the export.
Conclusion
In this blog, we taught readers how they can export Office 365 to MBOX format. Additionally, we described the MBOX family of files and gave instructions on using Gmail and Thunderbird to perform the task. Moreover, we saw why the manual process causes many problems and gave an accurate alternative.
Frequently Asked Questions on Office 365 to MBOX Transition
How long will it take to set up my Office 365 account in Thunderbird and begin the export take?
There is no fixed timeline common to all. Instead, it varies and is a factor of multiple components like your machine speed, available bandwidth, the number of emails in your account, etc. However, setting up the account is not that lengthy and should be completed within an hour or so. The real challenge comes in when the admin has to manually set up hundreds or even thousands of accounts industry-wide.
Is MBOX the only format in which I can maintain an offline backup of M365 emails?
No there are many different formats available like EML, PST, PDF, etc. Moreover, the professional tool provides access to all these formats in a single UI module.
How likely is it that MBOX gets corrupted in storage?
MBOX on the whole is quite a resilient file format and is less likely to corrupt than the PST format. However, as all the emails are kept in a single file when a corruption instance occurs it may spread to all email conversations. Thus making it nonusable. That is why you must select a trusted way to make an MBOX backup.