🚀 Migrating Gmail to Gmail Using Google Takeout + Thunderbird (Mac-Friendly)

🧩 Why I Did This
I had to move all my emails from a university Gmail account to my personal Gmail before the uni shut down my access. I wanted everything: attachments, threads, labels — you name it and my uni blocked access to the pop function so I could not fetch my emails from the server. Hence, I had to find a different route.

I used a combo of:

📦 Google Takeout
🕊️ Mozilla Thunderbird
💻 A MacBook
💡 A lot of trial and error

✳️ TL;DR Tools You’ll Need

✅ Google Takeout
✅ Thunderbird Mail Client
✅ Free Gmail account or your existing personal Gmail account
✅ Mac Terminal (caffeinate was a lifesaver)
✅ A bit of patience

📦 Step 1: Use Google Takeout to Export Old Gmail

1. Go to Google Takeout.

2. Click “Deselect all” — then scroll down and select only “Mail”.

3. Optional: You can click the “All Mail data included” button to pick specific labels.

4. Scroll down and click Next Step.

5. Choose:

6. Delivery method: Send download link via email

7. File type: .zip

8. File size: Set max to 2GB (⚠️ Thunderbird chokes on larger .mbox files)

9. Click Create export and wait. It might take a few hours depending on email volume. Google will email you a .zip file.

🗂️ Step 2: Unzip and Prepare MBOX File

Once downloaded:

• Unzip the archive

• You’ll find a folder like: Takeout > Mail > All mail including Spam and Trash.mbox

• Optional: Rename that .mbox file to something simple like: old-emails.mbox

🕊️ Step 3: Install Thunderbird and Set Up Import

1. Download and install Thunderbird

2. Open Thunderbird and create a new email account (login to your new Gmail or whatever account you are moving the emails to)

   • Use Gmail credentials (OAuth)
   • Allow Thunderbird access via your browser when prompted

3. Install ImportExportTools NG

   • Go to ☰ (hamburger menu) > Add-ons and Themes
   • Search for: ImportExportTools NG
   • Install and restart Thunderbird

📥 Step 4: Import MBOX to Thunderbird

1. In the left panel, right-click “Local Folders”

   • choose ImportExportTools NG
   • choose Import MBOX file
   • then “Individual mbox files”

2. Select your "old-emails.mbox" file

3. It should create a folder under Local Folders with your imported mail.
   ⚠️ Issue I faced: Thunderbird said “Import Done 0/1” or showed “No messages found.”
   ✅ Fix: I had to unzip the file manually and make sure the .mbox file was not inside a nested folder. Then I reimported. It worked.

✈️ Step 5: Copy Emails to Your New Gmail Inbox

1. Once the MBOX shows messages under Local Folders, you can drag and drop them into your Gmail account folders within Thunderbird. Example: Drag → Local Folders > old-emails Drop → [e-mail] > Inbox (or create a new folder)

💤 Pro tip: If you’re copying a lot, use Terminal’s caffeinate command to keep your Mac awake:

Error	Fix
MBOX import says 0/1	Rename MBOX file, make sure it's not zipped or inside subfolders
Thunderbird times out	Enable caffeinate, avoid sleep mode
Nothing appears after copy	Give it time — large volumes take a while to sync
Can't find “Import MBOX”	Must install ImportExportTools NG first
.mbox is >2GB	Go back to Takeout, split into smaller zip files (under 2GB)

✅ Final Tips

• Keep Gmail open in a browser to monitor sync progress.

• Thunderbird’s copy-paste to Gmail can take hours if you’re moving thousands of messages. Be patient — it works.

• Once migrated, you can label, archive, or search your emails from Gmail as usual.

🎉 Done!

You’ve successfully migrated your email like a pro — no scripts, no third-party sketchy tools, just solid open-source software and smart file handling.

📌 Want to Reuse This?

Feel free to fork or share this on your blog or dev space. You earned it. And your inbox is lighter — metaphorically.