MBOX to PST Converter

How to Convert MBOX to Office 365?

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    Summary: Office 365 enables you to work the way you want from virtually anywhere, no issue for data security, no extra time for managing mailbox and this is the reason that users are shifting their email client from MBOX to Office 365 (online Exchange). However, if you are planning to move the email client to cloud, it is equally important to move the database. Once Microsoft Outlook is installed on a system, it’s easy to import MBOX to Office 365 database— either use an indirect (two-step) solution or a software-based utility to import the data from one email client to another.  

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    Microsoft 365 is a subscription-based service, which is available with fully installed apps including Word, Excel, PowerPoint, etc., and these apps can be installed on multiple devices based on the licensing agreement or plan.

    These features along with a host of other software viz. Skype for Business, SharePoint, etc. are compelling the users to shift from MBOX to Microsoft 365 (cloud). Shifting the email client is not limited to application’s interfaces only, the users also need to import the respective database, and make sure that the database received after MBOX to Microsoft 365 conversion is complete and accessible. This blog post shares two methods to make a successful migration from MBOX to MS Office 365.

    Method 1: Migrate MBOX to Office 365 by using Thunderbird and Outlook

    This is an indirect method is comprised of two major steps, as follows:

    • Convert MBOX to Outlook PST
    • Export PST file to Microsoft 365 account

    Note: Both the applications must be installed on the same machine – Thunderbird and Microsoft Outlook.

    Step 1: Convert MBOX to PST

    1. Open the Thunderbird email client and select the required folder from the left panel of the screen.
    2. Go to right panel and select all the emails in that folder with ‘Ctrl+A.’
    Select Thunderbird folder; choose all emails with Ctrl+A.
    1. There is a blue highlighted message. Right click on the highlighted message and select the Save As option from the displayed menu
    2. Browse the location to save the folder and click ‘select folder.’Save highlighted message: Browse, select folder location
    3. Once the folder is saved, minimize the email client – Thunderbird and open Outlook
    4. Right-click on the folder in which the saved data is to be moved (emails from Thunderbird) and select the option – ‘Create a new folder.’
    5. Next, name the folder
    6. Go to Thunderbird again. Drag the saved folder and drop it in the recently created folder in Outlook
    7. Save the folder in PST format

    Step 2: Export PST file to Office 365 account

    Export PST to Office 365 with the help of Network Upload:

    1. Install Microsoft Azure AzCopy on the PC and create a copy of SAS URLmbox to outlook
    2. Upload recently created PST file
    3. View all emails in PST file
    4. Make a new mapping of PST data file and generate a PST import job in Exchange online account.
    outlook to mbox
    The indirect method has its list of drawbacks:
    1. It is mandatory for users to install Microsoft Outlook and Thunderbird on the same machine
    2. Helps in exporting the emails only, and cannot be used to transport other mailbox items
    3. Applies to Thunderbird primarily and does not support other MBOX files such as Apple Mail, Entourage, MuttMail, PocoMail, etc.
    4. The integrity of exported data (emails) is not guaranteed.
    5. Users should have adequate technical know-how of Microsoft 365, Azure Az and more.

    Method 2: Stellar Converter for MBOX

    1. The first step includes a selection of mail client. In this case, the mail client is Thunderbird.
      First step: Select Thunderbird as mail client
    2. Option to choose other email clients like Entourage, Apple Mail, etc. is also available
    3. Click ‘Select File’ to select the file for conversion. Alternatively, click Select Identity Folder to convert the contents of an entire folder.
      Choose email clients: Entourage, Apple Mail, etc. for conversion.
    4. Click the Convert button, and the scanning process startsConvert button: Scanning process starts.
    5. The scanned results will be shown as a preview. Verify the content of all the foldersPreview scanned results, verify folder content
    6. Once the scanning is complete, click the Save A dialog box with ‘Save File Options’ is displayed on the screen
    7. Tick mark the option ‘Office 365’and click OKSave File Options: Tick 'Office 365' and click OK
    8. The entire mailbox data including emails, journals, calendars, contacts and more are exported to Office 365 directly. Also helps in migration of all the attachments appended with the emails
    Free Download for Windows

    The direct software-based method is quick, easy, and reliable. The users do not need to follow the indirect method and complicated steps therein, to first convert the mail items into PST format.
    Most importantly, users do not have to deal with cases wherein data is only partially exported.

    The software-based utility helps convert a majority of email clients such as Spicebird, Pocomail, AppleMail, Gmail, Eudora, Mulberry, SeaMonkey, Netscape, ClawsMail, OperaMail, Mozilla Mail, Evolution, Sylpheed, Cone, Mutt, and Gnu Mail.


    Conversion of mailbox data from one email client to another is a necessary prerequisite when a user shifts to a new email client, for example migrating from Thunderbird to Outlook. As discussed in this blog post, the manual method consists of lengthy, time taking, and unwieldy steps, with chances of partial export and errors.

    User’s Mailbox data is vital, and, thus, for complete and accurate conversion of MBOX to Microsoft 365 data results, it is recommended to use a professional MBOX conversion software.

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    About The Author

    Eric Simson linkdin

    Eric Simson is an Email Platform Consultant and is associated with Stellar Data Recovery from last 6 years. He writes about the latest technology tips and provides custom solutions related to MS Outlook, MS Exchange Server, Office 365, and many other Email Clients & Servers.


    1. Pingback: Jack
    2. I used so many third party tools before but the best thing I found about your tool is that we can view and also save the detailed log report. Means nothing is hidden.

    3. When I tried to open MBOX mails, I received an error message that “mailbox file doesn’t exist”. I already checked the location of MBOX file, its available in original location. But still the application cannot read the MBOX file.
      Please provide solution.

      1. To fix MBOX issue, you can go for a reliable tool like Stellar Converter for MBOX to export complete MBOX file data into Outlook data file format.

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