Best Methods to Migrate Thunderbird to Office 365 in 2025

If you are looking for the best ways to migrate Thunderbird to Office 365. Here, we will explain both free and professional solutions to import MBOX files from Thunderbird into Microsoft 365 mailboxes. We’ll also compare Thunderbird and Office 365 to help you understand why many users are switching to the cloud-based platform.

Thunderbird vs. Office 365 – A Quick Comparison

Before you start the migration, it’s important to know why users prefer Office 365 over Thunderbird.

 

Features	Thunderbird	Office 365
Email Support	POP/IMAP/SMTP, multiple accounts	Exchange, IMAP/SMTP, advanced Microsoft 365 support
Type	Open-source email client	Cloud-based productivity suite
Cost	Free (Best for Individual users)	Paid (monthly/yearly basis), best for Business or enterprise users
Calendars & Tasks	Yes (minimal integration)	Yes (deep integration with Outlook & Teams)
Cloud Integration	Limited	Better Integration with apps, like OneDrive, SharePoint, Teams, etc.
Security	Good (S/MIME, PGP support via add-ons)	Enterprise-grade security, admin control, compliance
Collaboration	Minimal	Extensive (Teams, Word, Excel, PowerPoint, etc.)
Best For	Individual Users	Businesses, enterprises, collaboration-heavy work

 

If you need advanced features, seamless collaboration, and enterprise-grade security, moving from Thunderbird to Microsoft 365 is the smarter choice.

Methods to Migrate Thunderbird to Office 365

There are two main ways to move your data:

1. Manual Method – Free but time-consuming and limited.
2. Professional Method – Paid, fast, and without restrictions.

1. Free Manual Method to Import MBOX to Office 365

The manual process involves two stages:

Stage 1 – Save Thunderbird Emails as EML Files:

1. First, open the Thunderbird email client on your system.
2. Then, select the folder you want to export.
3. Now, highlight all emails, right-click, and choose Save As.
4. Next, pick a destination folder to save the emails in EML format.

Stage 2 – Import EML to Office 365 via Outlook:

1. Set up an Outlook profile with your Office 365 account.
2. Next, drag and drop the EML files into the desired Office 365 mailbox folder.

Note: This method doesn’t allow selective migration, and you can only move limited data at a time.

2. Professional Method – Migrate Without Limitations

If manual migration seems harsh, you can choose the Shoviv MBOX to Office 365 Migration Tool. The tool is one of the most reliable solutions, which allows you to import multiple MBOX files directly into Office 365 mailboxes without size or data loss issues.

Key Features:

• The tool is capable of batch migration of multiple MBOX files.
• It also supports MBOX conversion to PST, MSG, and EML formats.
• The tool provides some built-in filters to migrate particular items.
• It has a simple and user-friendly interface.

Quick Steps to Migrate Thunderbird to Office 365:

1. First, launch the Shoviv MBOX to Office 365 Migration Tool.
2. Then, click the Add button to load your MBOX files or folders.
3. Select the Office 365 option from the ribbon bar.
4. Now, put down your Office 365 login details.
5. Next, apply filters if needed.
6. Click Finish to start migration.

Conclusion

To migrate Thunderbird to Office 365, you can use either the manual method or a professional tool. While the manual way works for small data sets, it has many limitations. For a faster, error-free, and unlimited migration, the Shoviv MBOX to Office 365 Migration Tool is the best choice. You can even try its free demo to migrate the first 50 items per folder before purchasing.