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Thunderbird Not Working With Gmail? Here’s How to Fix It (2025 Update)

  Mohit Kumar Jha
Written By Mohit Kumar Jha
Anuraag Singh
Approved By Anuraag Singh
Modified On October 14th, 2025
Reading Time 8 Min Read

Emails stop syncing, Gmail refuses to connect, and Thunderbird keeps showing “IMAP Authentication Failed.” That’s exactly what I faced recently when I needed to send an urgent message. After troubleshooting, I found the problem wasn’t Thunderbird itself but Google’s new security rules. In this discussion, I’ll explain why Thunderbird not working with Gmail and share the steps to fix it quickly.

So, let’s go through:

Why Thunderbird Does Not Work with Gmail?

In 2024, Google began enforcing OAuth2 authentication for Gmail access. That means apps like Thunderbird can no longer log in using your regular username and password. If your Thunderbird is still using “Normal Password” instead of OAuth2, Gmail blocks the connection.

Now, What Is OAuth2 (OAuth 2.0)?

Open Authorisation 2.0 (OAuth2) is a modern authentication standard that allows applications like Thunderbird to connect to services such as Gmail without using the user’s actual password.

Instead of storing your Gmail username and password inside Thunderbird, OAuth2 works by giving Thunderbird a temporary access token (kind of like a digital key).

So when Thunderbird uses OAuth2 to connect:

  • You log in to Gmail through Google’s secure login page, not inside Thunderbird.
  • Google verifies your identity and gives Thunderbird a secure access token.
  • Thunderbird uses that token to fetch and send emails on your behalf.

Not only OAuth2, but there are other reasons also for why Thunderbird Not Working With Gmail:

  1. The “Less Secure Apps” setting was officially removed, so old password-based connections no longer work.
  2. Older Thunderbird versions don’t support Google’s latest OAuth2 standards.
  3. Cached credentials from older sessions can interfere with the new login method.
  4. If you recently enabled 2FA in Gmail, Thunderbird must reauthorise through Google’s sign-in flow.
  5. Firewall or antivirus software sometimes blocks Thunderbird’s outgoing connection to Gmail servers.

How to Fix Thunderbird Not Working With Gmail?

When Thunderbird stopped syncing my Gmail account, I found these step-by-step instructions effective, i.e. 

Step 1. Verify Gmail IMAP Settings

Thunderbird relies on IMAP to sync messages between Gmail and the client. So, make sure IMAP is enabled in your Gmail account:

  1. Log in to your Gmail account in a web browser.
  2. Click the gear icon > See all settings > Forwarding and POP/IMAP tab.
  3. Under “IMAP Access,” make sure Enable IMAP is selected.
  4. Auto-Expunge (optional) is selected, as it keeps the server updated immediately when you delete messages.
  5. Click Save Changes.

If IMAP is disabled, Thunderbird won’t be able to retrieve or send any messages until you enable it. So, this step is necessary to be followed.

Step 2. Update Thunderbird’s Server Settings

Thunderbird not working with Gmail sometimes occurs when server settings is misconfigured. Now, double-check the incoming (IMAP) and outgoing (SMTP) server configurations in Thunderbird by:

  • In Thunderbird, click on Tools > Account Settings > Server Settings.
  • Verify the following details for Gmail:
    • Incoming Mail (IMAP):
      • Server: imap.gmail.com
      • Port: 993
      • Connection Security: SSL/TLS
      • Authentication Method: OAuth2
      • Username: Full Gmail address
  • Outgoing Mail (SMTP):
      • Server: smtp.gmail.com
      • Port: 465 (SSL) or 587 (STARTTLS)
      • Connection Security: SSL/TLS or STARTTLS
      • Authentication Method: OAuth2
      • Username: Full Gmail address
  • Click OK to save the settings.

If the authentication method is set to “Normal Password” instead of “OAuth2.” Switching to OAuth2 immediately fixed the login issue.

Step 3. Re-Authenticate with Gmail

If your Gmail password was changed recently or you enabled two-factor authentication, Thunderbird need to reauthorise your account, until you see Thunderbird not working with Gmail. So:

  1. Open Thunderbird and select your Gmail account.
  2. When prompted to log in, a Google Sign-In window should appear.
  3. Enter your Gmail credentials, and allow Thunderbird to access the mail.
  4. Once done, Thunderbird will store an OAuth token instead of your password.

If you don’t see the Google Sign-In pop-up, remove the saved password:

  • Go to Tools.
  • Click on the Settings tab.
  • Afterwards, hit the Privacy & Security, and select the Saved Passwords option.
  • Now, Remove Saved Logins related to Gmail, and Restart Thunderbird & try again.

Step 4. Allow Access to Less Secure Apps

Although Google phased out “Less Secure Apps” settings, older Thunderbird versions still require this fix. For the same:

  • Visit: https://myaccount.google.com/lesssecureapps
  • Temporarily turn it ON, log in via Thunderbird, then disable it again once connected.

This is the most straightforward trick to resolve the Thunderbird not working with Gmail issue. 

Step 5. Check Google Account Security Alerts

Sometimes, Google blocks Thunderbird’s sign-in attempt for security reasons. To fix:

  • Open Gmail in a browser.
  • Look for a security alert.
  • Click “Yes, it was me” or “Allow access.”

Then, try reconnecting in Thunderbird.

Step 6. Temporarily Disable Antivirus or Firewall

Sometimes the firewall blocks Thunderbird’s access to Gmail servers. You can test this by:

  1. Temporarily disabling antivirus/firewall.
  2. Restart Thunderbird and check if Gmail synced successfully.

If it worked, add Thunderbird as an exception in your firewall settings to prevent configuration issues in future.

Step 7. Back Up Your Gmail Data

While I was troubleshooting, I was so focused on fixing Thunderbird Not Working With Gmail. But at some point in time, I realised what if something went wrong and I lost access to all those messages in Thunderbird? 

When this question is tackled in my mind, I decided that before making any big configuration changes, it’s necessary to have a backup.

Now, I’m not talking about manually exporting folders one by one, because it takes time with large data like mine. Instead, I use a simple SysTools IMAP Backup Tool that automatically downloads all my Gmail emails to my computer, without errors and technical know-how.

Plus, I can save my messages in multiple formats like PST, MBOX, MSG, PDF or EML, which makes it easy to import them into another email client if needed.

If you’re switching to a new Thunderbird profile or authentication methods, I’d highly recommend running a quick backup first to safeguard your data.

Step 8. Create a New Thunderbird Profile

If nothing worked, create a new Thunderbird profile, and it will finally solve the Thunderbird Not Working With Gmail:

  1. Press Windows + R, type thunderbird.exe -P, and press Enter.
  2. Click Create Profile, name it, and follow the steps.
  3. Add your Gmail account again with the correct IMAP/SMTP settings.

After this, Thunderbird connected smoothly to Gmail. You can delete IMAP account, if not needed after creating a new account.

Now, Learn Common Thunderbird + Gmail Error Messages

Here are different error messages with quick fixes for both Gmail and Thunderbird: 

Error Message What It Means Quick Fix
Authentication failed Gmail rejected user credentials Change auth type to OAuth2
Login to server imap.gmail.com failed OAuth token expired or blocked Re-authenticate with the Gmail pop-up
Unable to connect to server Firewall or wrong port issue Check ports and allow Thunderbird
Sending of password did not succeed Google blocked password-based login Use OAuth2 authentication
What’s Changed Recently – Thunderbird Not Working With Gmail (2025 Update)

While researching this issue, I found something new: 

  • Google has completely removed legacy authentication, and OAuth2 is now mandatory.
  • Workspace admins can control which third-party apps, like Thunderbird, are allowed to connect. 
  • Older Thunderbird builds (pre-v91) do not support OAuth2 properly. You’ll need to upgrade to connect again.

Therefore, if Thunderbird can’t configure with Gmail, 90% of the time it’s an OAuth problem, not an IMAP issue.

How to Keep Gmail Working Smoothly in Thunderbird

After fixing the issue, make a few changes to prevent future problems:

  • Keep Thunderbird updated.
  • Remove saved credentials whenever changes in the Gmail password.
  • Monitor Google’s security alerts regularly to allow new device logins quickly.

Since then, Thunderbird and Gmail have worked together flawlessly.

Author’s Verdict

If your Thunderbird not working with Gmail, don’t panic; the fix is simple once you understand Google’s new rules, which we discussed in this guide. In my case, switching to OAuth2 resolved the issue. 

To summarise:

  • Update Thunderbird to the latest version
  • Set authentication to OAuth2 for IMAP and SMTP
  • Re-sign in using the Google pop-up
  • Approve any security alerts in Gmail
  • Backup or archive IMAP email locally
  • Add firewall exceptions

Once you follow these steps, Gmail syncs instantly, without any ifs or buts.

People Also Ask

Q1. Does Thunderbird support Gmail with 2-Step Verification?
Yes, but you must use OAuth2, not the old password method.

Q2. Why does Thunderbird keep asking for my Gmail password?
It’s usually because OAuth2 isn’t configured, or the token has expired. Re-authenticate through the pop-up.

Q3. My company Gmail doesn’t connect with Thunderbird. What should I do?
If it’s a Google Workspace account, contact your IT admin to ensure Thunderbird is allowed as a trusted OAuth app.

  author

By Mohit Kumar Jha

Mohit is a Microsoft Certified expert for all things Microsoft. He brings a unique perspective gained from nearly a decade of active participation in various IT forums, blogs, and social media. Known in admin circles as the go-to guru for solving user queries in the domain of email and cloud migration, data backup, and digital forensics. The secret to his core expertise lies in solving problems practically. Through this hands-on experience, he has acquired knowledge in diverse domains like Microsoft 365 Cloud, On-Premise Exchange Server, AD, and Entra ID.