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How to Fix Can’t Verify Gmail in Thunderbird on Windows 11: Step-by-Step Solutions

If you are trying to use Gmail in Thunderbird on Windows 11 but see an error saying “Can’t verify Gmail,” it can be frustrating. This problem usually happens because Thunderbird cannot connect properly to your Gmail account. There are several simple reasons why this might occur.

Fortunately, fixing this issue is often straightforward. You just need to adjust some settings in Gmail and Thunderbird to ensure they communicate securely. This guide will walk you through easy, step-by-step solutions.

By following these instructions carefully, you will be able to set up Gmail in Thunderbird without verification errors. Let’s get started with some quick checks.

These steps are designed for anyone, even if you are not very technical. Take your time, and you will have your Gmail working smoothly in Thunderbird soon.

Quick Note: Prerequisites and Basic Checks

  • Check your internet connection: A stable internet connection is essential for Thunderbird to connect to Gmail servers.
  • Update Thunderbird: Make sure you are using the latest version of Thunderbird to avoid compatibility issues.
  • Enable IMAP in Gmail: Gmail must have IMAP enabled in your account settings for Thunderbird to access your emails.
  • Use correct Gmail credentials: Double-check that your email and password are entered correctly.

Step 1: Enable IMAP in Your Gmail Account

IMAP is a protocol that allows email clients like Thunderbird to access your Gmail messages. If IMAP is not enabled, Thunderbird cannot sync your emails.

  1. Open your web browser and go to Gmail.
  2. Log into your Gmail account.
  3. Click the gear icon in the top right corner and select See all settings.
  4. Navigate to the Forwarding and POP/IMAP tab.
  5. Scroll down to the IMAP access section.
  6. Select Enable IMAP.
  7. Click Save Changes at the bottom of the page.

Enabling IMAP is important because it allows Thunderbird to read and sync your Gmail emails in real time.

Step 2: Allow Less Secure Apps or Use App Passwords

Gmail has security settings that can block apps like Thunderbird if it thinks they are less secure. Depending on your account security, you may need to allow Thunderbird access.

Option A: Use an App Password (Recommended)

If you have 2-Step Verification enabled on your Google account, you cannot use your normal password in Thunderbird. Instead, create an app password:

  1. Go to your Google Account settings at https://myaccount.google.com/security.
  2. Under Signing in to Google, select App Passwords. You may need to sign in again.
  3. Choose Mail as the app and Windows Computer as the device, then click Generate.
  4. Copy the 16-character app password provided.
  5. In Thunderbird, when prompted for your Gmail password, paste this app password instead of your normal password.

Using an app password improves security while allowing Thunderbird to access your Gmail.

Option B: Allow Less Secure Apps (If You Don’t Use 2-Step Verification)

Google is phasing out this option, but if still available, you can enable access for less secure apps:

  1. Visit https://myaccount.google.com/lesssecureapps.
  2. Toggle the setting to allow less secure apps.
  3. Try signing into Thunderbird again.

This option is less secure and should only be used if you do not have 2-step verification enabled.

Step 3: Verify Thunderbird Account Settings

Ensure that your Gmail account is set up correctly in Thunderbird with the proper server settings.

  1. Open Thunderbird.
  2. Go to Tools (or the menu icon) > Account Settings.
  3. Select your Gmail account from the list.
  4. Check the Server Settings:
    • Server Type: IMAP Mail Server
    • Server Name: imap.gmail.com
    • Port: 993
    • Connection Security: SSL/TLS
    • Authentication Method: OAuth2
  5. Next, check Outgoing Server (SMTP) settings:
    • Server Name: smtp.gmail.com
    • Port: 465 or 587
    • Connection Security: SSL/TLS or STARTTLS
    • Authentication Method: OAuth2

Correct server settings and using OAuth2 authentication are critical because they ensure Thunderbird connects securely and correctly to Gmail servers.

Step 4: Re-authenticate in Thunderbird

Sometimes, Thunderbird needs you to re-enter your Gmail credentials using the OAuth2 popup window.

  1. Remove your Gmail account from Thunderbird (make sure you have backups if needed).
  2. Restart Thunderbird.
  3. Add your Gmail account again:
    • Go to File > New > Existing Mail Account.
    • Enter your Gmail address and password (or app password if you use 2-Step Verification).
    • Thunderbird will open a Google sign-in popup. Sign in and allow permissions.

This process ensures Thunderbird obtains the correct authentication tokens to access your Gmail account.

Alternative Method: Use OAuth2 Authentication Manually

If you still face issues, manually setting the authentication method to OAuth2 can help:

  1. Open Account Settings in Thunderbird.
  2. Select your Gmail account, then go to Server Settings.
  3. Change Authentication Method to OAuth2.
  4. Do the same for the SMTP server settings.
  5. Save changes and restart Thunderbird.

OAuth2 is the recommended and most secure way to authenticate Gmail accounts in Thunderbird.

FAQs

Q: Why does Gmail say “Can’t verify” in Thunderbird?

This usually happens because Thunderbird cannot authenticate with Gmail’s servers. It can be due to incorrect passwords, disabled IMAP, outdated authentication methods, or security restrictions on your Google account.

Q: Is it safe to enable “less secure apps” in Gmail?

Not really. Allowing less secure apps lowers your account security. It is better to use app passwords or OAuth2 authentication.

Q: What if I don’t have 2-Step Verification enabled?

You can either enable it for better security and use app passwords, or in some cases, allow less secure apps (though this option is being removed by Google).

Q: Can antivirus or firewall settings affect Gmail verification in Thunderbird?

Yes. Sometimes antivirus or firewall software blocks Thunderbird’s connection to Gmail servers. Temporarily disabling these or adding exceptions may help.

Q: Will updating Thunderbird fix this issue?

Often, yes. Newer versions of Thunderbird support OAuth2 better and fix bugs related to Gmail authentication.

When Nothing Works

If you have tried all the above steps and still cannot verify your Gmail account in Thunderbird, consider these final options:

  • Check Google’s Account Security Alerts: Sometimes Google blocks sign-ins it sees as suspicious. Visit Security Checkup to review and allow access.
  • Reset Your Google Account Password: Sometimes resetting your password can resolve authentication issues.
  • Consult Thunderbird Support Forums: The official Thunderbird support has helpful tips and community assistance.
  • Consider Using Gmail Web or Another Email Client Temporarily: Until the issue is resolved, you may want to use the Gmail web interface or a different email client.

Conclusion

“Can’t verify Gmail” errors in Thunderbird on Windows 11 are common but usually easy to fix. The key steps are enabling IMAP in Gmail, using the correct authentication method (preferably OAuth2), and ensuring app passwords are used if 2-Step Verification is enabled.

Always double-check your account settings and keep Thunderbird updated. By following the step-by-step solutions here, you should be able to resolve verification problems and keep your Gmail working smoothly in Thunderbird.

If problems persist, use official Google and Thunderbird resources or support forums for more help. With patience and careful setup, your email experience will be seamless and secure.

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