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How to Migrate PostBox Email Data to Office 365?

Bhawna Barwal | Email Conversion email migration file conversion How to's Software Technology | 4 minutes read | Modified on: 14-04-2026

Want to migrate Postbox email data to Office 365? Then this is the right place for you. In this blog, we will explore two effective ways to import Postbox emails into Office 365: using an Postbox to Office 365 converter and manual method. If you are using Postbox as your email client and planning to move your data to Office 365, you may encounter a compatibility challenge. Postbox stores emails in MBOX format. To successfully complete this migration, you need to convert MBOX Postbox files into Office 365.

Office 365: A cloud-based mailbox system that uses Exchange online and does not directly support MBOX imports. Because of this incompatibility, conversion of file formats is required.

Method 1: Using Postbox to Office 365 Converter to Migrate email data to Office 365

Professional CubexSoft MBOX to Office 365 Converter – The most efficient and hassle-free way to import Postbox emails into Office 365. The tool helps to directly migrate Postbox data into Office 365 accounts. The tool supports bulk uploads, allowing you to import multiple files at once. It is an efficient method that keeps all properties intact during conversion. And it can independently move Postox to Office 365, without installation of any email client. Also, it is an easy-to-use method, users can simply utilize it without any technical skill. Users can download this tool on Windows (Windows OS editions 11, 10, 8, 7, 8.2, Vista, XP, etc) and Mac Operating Systems such as Monterey, Catalina, High-Sierra, Mojave, Big-Sur, Ventura, etc. Free demo edition of the app enables users import 25 emails from Postbox to Office 365 without paying any charge. Click on this link and get a trial for free.

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Steps to Migrate PostBox Email Data to Office 365

1. Extract MBOX Files from Postbox

Postbox stores emails locally in MBOX format. To locate them:

  1. Open Postbox
  2. Go to Account Settings
  3. Navigate to Local Folders
  4. Locate the directory where MBOX files are stored
  5. Copy the required MBOX files to a safe location.

2. Install and Launch the Converter Tool

  • Download the reliable MBOX Converter tool and install it on your system.
  • Launch the application once installation is complete.

3. Add MBOX Files

  • Click on Add File then Select Files or Select Foder.
  • Select the MBOX files extracted from Postbox

4. Preview Email Data

The tool provides a preview feature. You can:

  • View emails
  • Check attachments
  • Verify folder structure
  • This ensures you are importing the correct data.

5. Choose Office 365 as Saving Option

  • Select Office 365 as the output option
  • Enter your Office 365 credentials (email and password)

6. Apply Filters

This advanced tool allows you to:

  • Filter emails by date
  • Exclude specific folders
  • Skip attachments

This helps in selective migration.

7. Start the Migration

Click on Convert to start the migration.

Benefits of Using Postbox to Office 365 Converter Tool

  • Direct migration to Office 365
  • Saves time and effort
  • Maintains folder hierarchy and metadata
  • Supports bulk migration
  • Reduces risk of data loss

Method 2: Manual Method (Using Thunderbird and Outlook)

User can go with a manual method involving Thunderbird and Outlook. This process is longer and requires careful execution and it is also feasible for small numbers of files.

Make It Sure:

  • Postbox installed
  • Thunderbird installed
  • Microsoft Outlook installed and configured with Office 365 account
  • ImportExportTools NG add-on for Thunderbird

Manual Process of Migrating from Postbox to Office 365

Step 1: Import MBOX into Thunderbird

  1. Open Thunderbird
  2. Install ImportExportTools NG.
  3. Go to Add-ons Manager
  4. Search for the add-on
  5. Install and restart Thunderbird
  6. Import MBOX files:
  7. Right-click on Local Folders
  8. Select ImportExportTools NG > Import MBOX file
  9. Choose your Postbox MBOX files

Step 2: Move Emails to Thunderbird Account

Drag imported emails into a configured email account in Thunderbird (IMAP-based)

Step 3: Sync Emails to Server

Thunderbird will sync emails with the mail server. Ensure synchronization is complete before proceeding.

Step 4: Access Emails in Outlook

  1. Open Outlook configured with the same Office 365 account
  2. Allow it to sync with the server
  3. Emails uploaded via Thunderbird will appear in Outlook

Step 5: Organize Emails in Office 365

  1. Log in to Office 365
  2. Verify emails and folder structure
  3. Reorganize if necessary

Restrictions in Manual Process

  1. Time-consuming and complex
  2. Requires multiple applications
  3. Risk of syncing errors
  4. Not ideal for large mailboxes
  5. May not preserve folder hierarchy perfectly

Read more

How to Import MailPile Data to Outlook

How to Migrate data from Spicebird to Outlook

How to Transfer Emails from Sylpheed to Office 365

Conclusion

Postbox to Office 365 converter method is the most efficient and reliable option, especially for businesses or users dealing with large volumes of email data. It simplifies the process and minimizes risks. On the other hand, the manual method provides a cost-effective. However, it requires more time, patience, and technical understanding. By following the methods outlined in this guide, you can successfully migrate your emails from Postbox to Office 365 without losing valuable information. If you want a quick and seamless experience, using the professional converter tool is highly recommended. For smaller tasks or one-time migrations, the manual method can still be a viable solution when executed carefully.