Mozilla Thunderbird saves its data in MBOX file format. An MBOX file contains Emails, attachments, calendars, and contacts of Thunderbird. Unfortunately, Office 365 doesn't support the MBOX file format. So there is a need for Thunderbird to Office 365 migration. We are providing two techniques for this migration. The first technique is manual, and the other is automated to migrate Thunderbird email to Office 365. We will also talk about a utility for this migration which is Sysinfo MBOX Converter. But before discussing the methods, let's know some reasons for this migration.

Why We Need to Import Emails from Thunderbird to Office 365

Some of the reasons are given below for moving from Mozilla Thunderbird to Microsoft Office 365.

Provides additional features for data sharing, storage, communication, and collaboration.
Migrate or move Thunderbird Mail to Office 365 to use Microsoft Cloud services on a monthly rental.
It is more secure and data storage benefits with O365 cloud servers.
You can read emails on mobile or tablet devices through a browser.
Provides Office applications such as Word, Excel, Access, Skype, and Exchange server are included.

The above are reasons to migrate Thunderbird email to Office 365. Now let’s move ahead to the methods of this migration.

Migrate from Thunderbird to Office 365 Manually

We can not perform this migration in a single run. So we are dividing this method into two phases. In the first phase, we will convert Thunderbird emails into EML format. And in the second phase, we will import EML files to Office 365 Account. Let's start with the first phase.

Transfer Thunderbird Emails in EML Format

In this phase, we will transfer Thunderbird emails into EML file format. Let's discuss the steps:

Firstly, Create a new folder on your desktop.
Then, Run Mozilla Thunderbird software.
After that, Go to the mailbox folder from where you want to migrate the emails.
Now, select the emails from the mailbox folder.
Then, Right-click on the selected emails and choose the Save As option.
Here, browse the desktop folder which is recently created and click on the Select folder button to save Thunderbird emails into EML formats.

So we have transferred the Thunderbird emails into EML format. Now move toward the second phase.

Import EML Files to Office 365 Account

Here, we will log in to the Office 365 email account and open the associated Outlook application.

Firstly, Launch the Office 365-associated Outlook application.
Then, create a new folder in the Outlook wizard and Name that newly created folder.
Now, drag the EML file from the desktop into the newly created folder.

So that, your Thunderbird MBOX file is transferred to Office 365. But there may be limitations to this method. Let’s discuss them.

Limitation:-

The possible limitations of the manual method are given below.

It takes a lot of time to migrate emails from Thunderbird to Office 365
It may be tricky for novice users and allows users to migrate a limited amount of emails.
This manual approach doesn't maintain the data integrity and folder structure of Thunderbird folders.
When you are performing conversion in bulk, there is a possibility of data loss.

Due to these limitations, many non-technical users don’t perform Thunderbird to Outlook 365 migration. For those users, let’s know another method which is an automated solution.

Automated Approach to Export Thunderbird Emails to Office 365

Many users will not be able to use the manual method due to its limitations. So they can go with this automated solution. Here, we are going to use a most efficient utility named Sysinfo MBOX Converter. Furthermore, This utility is competent enough to migrate Thunderbird emails into many other email clients like Gmail, Yahoo Mail, GoDaddy Email, HostGator Email, iCloud, etc.

Concussion

In this blog, we have seen a brief introduction to Mozilla Thunderbird and Office 365 email clients. Then we have seen reasons to Import Emails from Thunderbird to Office 365. Furthermore. We have discussed manual and automated approaches. Both methods are good to perform. However, manual methods have limitations. So we recommend you go with the automated solution.