How to Import MBOX to Office 365 Easily: Step-by-Step Guide

Jackson Strong | September 30th, 2025 | Email Migration, Office 365

Are you looking for a way to import MBOX to Office 365? It can be a bit tricky because Microsoft 365 doesn’t natively support MBOX files, but now you are at the right place. In this guide, you’ll learn how to migrate MBOX to Office 365 using both manual and automated methods. So, follow the explored instructions to complete MBOX to Office 365 migration process.

Table of Contents

Why Import MBOX to Office 365?

MBOX files are widely used to store email messages from clients like Thunderbird, Apple Mail, and others. However, Microsoft Outlook 365 uses Exchange Online mailboxes, which don’t support direct MBOX import.

Users typically upload MBOX to Office 365 for reasons such as:

  • Centralized email management with Microsoft 365
  • Easy accessibility from any device
  • Data backup and cloud storage
  • Transitioning from an old email client

How to Migrate MBOX to Office 365 Manually?

Since Office 365 doesn’t recognize MBOX files directly, the only manual workaround is through Mozilla Thunderbird.

Prerequisites:

  • Mozilla Thunderbird installed
  • Your Office 365 account credentials
  • MBOX file ready

Step 1. Open Thunderbird and skip the new account setup.

Open Thunderbird

Step 2. Add your Office 365 email manually using your login details.

Add your Office 365 email manually

Step 3. Restart Thunderbird and install the ImportExportTools NG add-on.

Restart Thunderbird and install the ImportExportTools NG add-on

Step 4. Right-click on Local Folders > ImportExportTools NG > Import MBOX File.

Local Folders > ImportExportTools NG > Import MBOX File

Step 5. Select your MBOX file and load it.

Select your MBOX file

Step 6. Once emails appear, right-click the imported folder > Move To > your Office 365 email.

import mbox to office 365

This method helps you migrate emails from MBOX to Office 365 manually.

Limitations of Manual Method

While the manual approach works, it has several practical drawbacks:

  • Takes a lot of time for large or multiple MBOX files.
  • Requires technical setup and Thunderbird configuration.
  • No way to filter emails (e.g., by date, sender, or subject).
  • Risk of losing folder hierarchy or attachments.
  • Thunderbird may freeze or crash when handling large data.

Because of these challenges, most users prefer a simpler and faster solution.

How to Import MBOX to Outlook 365? (Best for All Users)

If you have multiple MBOX files or want a smooth, error-free migration, using an automated MBOX to Office 365 migration tool is the best option. These tools directly connect to your Office 365 mailbox and securely upload all MBOX emails, maintaining the folder structure and attachments. Unlike the manual process, they don’t require Thunderbird setup or extra add-ons.

One such reliable solution is Advik MBOX Migrator. This smart tool allows you to import MBOX to Office 365 with just a few clicks. It ensures complete data accuracy, preserves folder hierarchy, and transfers all emails with attachments safely. Whether you’re migrating a single file or multiple mailboxes, this MBOX to Office 365 Migrator simplifies the entire process without any technical hassle.

Download and try the software for free.

 

Note: Unable to Sign in?. Click here for the instructions.

Steps to Import MBOX to Office 365

Step 1. Run the tool and add .mbox file.

run the software

Step 2. Select MBOX folders and click Next.

choose the required MBOX email folders

Step 3. Next, select Office 365 as a saving option from the list.

select office 365 as saving option

Step 4. Enter Office 365 login credentials & click the Convert button.

enter office 365 account details & click convert

Step 5. Software will start uploading emails from .mbox into Office 365.

analyze the MBOX to Office 365 migration process

Once done, log in to your Microsoft 365 mailbox — all your MBOX emails will appear with the same structure as before.

Watch How to Upload MBOX to Office 365 Automatically

Overall, this software is the ultimate solution for transferring data from mailboxes. 

Why Choose MBOX to Office 365 Migration Tool?

Let’s check out some other benefits of using this utility. Some of them are;

  • The simplest user interface for technical and non-technical users.
  • Batch import MBOX into Outlook 365 account in a single attempt.
  • Maintain mailbox folder hierarchy and key elements of MBOX file.
  • Also, this tool offers to repair MBOX file, whether it is damaged or corrupted.
  • Export MBOX to 20+ file formats; convert MBOX to PST, EML, PDF, MSG, etc.
  • Preserve Metadata and other mailbox items such as To/From, subject, Cc, etc.
  • Also, extract emails from MBOX file with attachments.
  • No size limit — migrate large MBOX files without any issue.
  • Option to import MBOX files to multiple Office 365 accounts.
  • Supports MBOX files from all email clients (Thunderbird, Apple Mail, Opera Mail, etc.).
  • Advanced filter options to import specific emails by date, subject, or sender.
  • Auto-detect MBOX files from system for quicker setup.
  • Generates a complete migration report after the process is finished.
  • Works with all Windows versions, including Windows 11, 10, 8, 7.

Conclusion

In this post, we have discussed how to import MBOX to Office 365 account using two different methods. Manually importing MBOX  file to Office 365 through Thunderbird is possible, but not practical for large data or multiple files. The process is lengthy, requires technical know-how, and risks data inconsistency.

If you want a reliable and time-saving approach, use an MBOX to Office 365 migrator tool. It ensures all your emails, attachments, and folders are safely imported to your Outlook 365 account without losing anything.

Frequently Asked Questions (FAQs)

Q1. Does Microsoft 365 support MBOX files directly?

Ans. No. Office 365 doesn’t import MBOX files natively. You must use Thunderbird or an MBOX to Office 365 migrator tool.

Q2. Can I import multiple MBOX files at once?

Ans. Manual import supports one file at a time. Automated tools can handle multiple files in a single go.

Q3. Do I need Thunderbird installed for automated migration?

Ans. No. A professional migrator can import MBOX to Office 365 without using Thunderbird.

Q4. Will the folder hierarchy remain the same after migration?

Ans. Yes. A good MBOX to Office 365 migration tool preserves the exact folder structure.

Q5. Can I apply filters to transfer specific emails only?

Ans. Yes. Many tools allow filtering by date, sender, or subject before migration.

Q6. Does this software allow to import more than 15 GB MBOX files to Outlook 365?

Ans. Yes, there is no size limit. The tool is suitable for importing more than 15 GB MBOX files without any data loss.