Step-by-Step Guide for Thunderbird to G Suite Migration

Thunderbird file 6

Thunderbird to G Suite Migration: Gmail offers several useful account functionalities such as free document sharing and collaborating, productivity tools, large storage capacity and access to multiple account functionalities at anytime, anywhere, etc. These functionalities prompt the users to migrate from other emailing platforms such as ‘Thunderbird’ to ‘Gmail’.

However, it is essential to import mailbox data while migrating from one email client to another.

The following methods help to import mailbox data from Thunderbird to Gmail

Thunderbird to G Suite

  1. Method 1: Use a software such as Stellar Converter for MBOX to convert Thunderbird (.mbox) file to Outlook (.pst) data file and import the PST file to Gmail through G Suite Migration for Microsoft Outlook (GSMMO).
  2. Method 2: Import Gmail file to Thunderbird account and then export Thunderbird file to Gmail.

Method 1: Convert Thunderbird file to Outlook data file and import Outlook file to Gmail

Step 1: Convert Thunderbird file to Outlook data file

1.Launch and open Stellar Converter for MBOX software

Thunderbird file 1
Thunderbird file 1

2.On homepage, click Email Client and select Thunderbird from the drop down list

Thunderbird file 2
Thunderbird file 2

3.Click Select File to select Thunderbird file for conversion. Click Convert to initiate conversion process

4.Once the software converts file format, it previews the file components in three-pane structure.

5. Verify email components. Go to File menu and click Save Converted File. A Save As pop-up appears 

Thunderbird file 3
Thunderbird file 3

6.Verify email components. Go to File menu and click Save Converted File. A Save As pop-up appears 

Thunderbird file 4
Thunderbird file 4

7. Click Next and the software saves data in new PST file.

Thunderbird file 5
Thunderbird file 5

     Step 2: Import PST to Gmail with GSMMO

1.Download and install GSSMO. Once the migration tool is installed, go to Windows Start menu and open GSMMO.

Thunderbird file 6
Thunderbird file 6

2. Sign-in to G Suite account. Create a G Suite account with valid user credentials and use this account to connect to GSMMO.

Thunderbird file 7
Thunderbird file 7

3.Choose Outlook data for import. Select the PST file to import data to Gmail. The migration tool can import multiple PST files with Control-Click option.

4. Specify data to import. Specify data to import – emails, contacts, calendar events or all. Uncheck Deleted items and Junk mail. Click Migrate to start Thunderbird to Gmail migration process.

5. Monitor PST to Gmail migration. GSMMO provides options such as ‘Pause and Resume migration’, ‘Restart migration’ and ‘My internet connection went away’ to help users to monitor data migration from Outlook data file to Gmail account

Method 2: Import Gmail file to Thunderbird account and then export Thunderbird file to Gmail

Prerequisites for restoring MBOX file to Gmail account

  • Enable Gmail account with IMAP protocol. Refer to the link.
  • Disable 2-step authentication for all users. Click the link to disable 2-step authentication of Gmail account.
  • Allow less secure apps with the help of this link.

Step 1 The first step is to create new email-setup in Thunderbird with existing Gmail account

  • On Menu bar, go to Tools and from the drop-down menu, click Account Settings
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Thunderbird file 8
  • On Account Settings page, click Account Actions followed by Add Mail Account and the Mail Account Setup page opens.
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Thunderbird file 9
  •  On Mail Account Setup page, enter your Gmail account’s name, email address and password and click Continue. Make sure IMAP is enabled and click Done.
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Thunderbird file 10
  • This step will configure Gmail account in Thunderbird. You will see your Gmail account on the left navigation bar and will start receiving all emails from your Gmail account into Thunderbird.
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Thunderbird file 11

With this, you have successfully created a Gmail account in Thunderbird.

Step2. Install Add-on ‘ImportExportTools’ for Thunderbird

  • Go to the link to download ImportExportTools utility for Thunderbird
  • Save the file at the same location as .xpi file of Thunderbird file
  • In Thunderbird, go to menu bar, click ‘Tools’ and click ‘Add-ons’
Thunderbird file 12
Thunderbird file 12
  • In Add-ons Manager tab, go to Gear icon and install Add-on from File
  • Locate .xpi file for Thunderbird and restart Thunderbird.

Step3. Extract the zipped Gmail email archive file provided for extracting data

  1. Download and extract Gmail email archive file in .ZIP format
  2. Extract the components of zip file. Once you have extracted, you will see several MBOX files, which are named corresponding to the label in Gmail.

Step4. Import emails from MBOX file to Gmail account

1. In Thunderbird, create a new folder such as gmail-mbox. To do so, go to Navigation Pane, right click Local Folders and click New Folder. Name the new folder as gmail-mbox

Thunderbird file 13
Thunderbird file 13

2.Right click on new folder, select ImportExportTools and Import MBOX file

3.Select Import directly one or more MBOX files and click OK

4. In Files browser, locate the folder where you’ve extracted Gmail MBOX files. Select the MBOX file that corresponds with new folder that you want to restore and click Open

5.All emails from that folder will start importing. It will take some time to load all emails.

6.In navigation pane, right click on Gmail account name and Click on New Folder as Label name for Gmail and name the label as Gmail-MBOX-New-File

Step5. Copy all imported emails to Gmail account

  1. In Thunderbird, go to navigation pane and expand Local Folders and then select the folder gmail-mbox to import all emails from Thunderbird to Gmail.
  2. In that folder select all emails and right-click the selection, and select ‘Copy to in a particular
  3. It will take some time to copy all emails from Thunderbird to Gmail account.
  4. Once done, login to your Gmail account online, and you should see all emails in the label of your Gmail account.


Thunderbird to G Suite – Importing mailbox data is essential when you are migrating from one email client to another. It is also essential to check protocols for both the email clients for establishing connectivity.

The post provides a step-by-step guide for migrating Thunderbird data to Gmail by converting Thunderbird (.mbox file) to Outlook (.pst file) with the help of MBOX to PST converter software , and exporting PST file to Gmail by using GSMMO. This method is fast and easy, and migrates multiple Thunderbird files to Gmail.

You can also migrate Thunderbird to G Suite by importing Gmail MBOX file to Thunderbird and exporting Thunderbird data back to Gmail account. However, the long list of steps in the process may puzzle the user during migration.

Also Read: What is VPS Hosting: Pros and Cons of VPS Hosting in 2020

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