Software⏱️ 3 min read📅 2026-06-11

How to Fix: Thunderbird Gmail IMAP error: Some messages could not be FETCHed (failure)

Thunderbird Gmail IMAP error: Some messages could not be FETCHed (failure) issue on OS X.

Quick Answer: Check the IMAP server settings and ensure that the mail server is configured correctly. Try resetting the IMAP connection or updating Thunderbird to the latest version.

📋 Table of Contents

  1. 🛑 Root Causes of the Error
  2. 🔧 Proven Troubleshooting Steps
  3. ✨ Wrapping Up

The 'Some messages could not be FETCHed (failure)' error in Thunderbird's Gmail IMAP connection is frustrating, especially when you can still receive new mail. This issue affects users who have set up their Gmail accounts in Thunderbird via IMAP and are experiencing difficulties updating the inbox.

This error occurs because of a misconfiguration or compatibility issue with the IMAP settings, leading to incomplete message fetching. To resolve this issue, we will explore two primary fix methods: checking IMAP server configuration and verifying mailbox permissions.

🛑 Root Causes of the Error

  • The main reason for this error is an incorrect IMAP server configuration. Thunderbird may not be correctly configured to handle the Gmail IMAP server's requirements, resulting in incomplete message fetching.
  • Another possible cause of this error is a permission issue with the mailbox. The IMAP server may not have granted Thunderbird the necessary permissions to access and fetch messages from the mailbox.

🔧 Proven Troubleshooting Steps

Verify and correct IMAP server configuration

  1. Step 1: Step 1: Check the Gmail IMAP settings in Thunderbird's Account Settings. Ensure that the 'Use secure connection' option is enabled, and make sure to enter the correct IMAP server address (imap.gmail.com) and port number (993).
  2. Step 2: Step 2: Verify that the correct Gmail account credentials are being used for the IMAP connection. Make sure to use the full Gmail address and password, as using only the username can lead to authentication issues.
  3. Step 3: Step 3: Check if any firewall or antivirus software is blocking the IMAP connection. Disable these programs temporarily while testing the connection.

Check mailbox permissions

  1. Step 1: Step 1: Log in to the Gmail account associated with Thunderbird's IMAP connection and verify that the mailbox has not been moved or deleted. Ensure that all messages are still present in the original mailbox.
  2. Step 2: Step 2: Check if any other email clients are using the same mailbox for IMAP access. If so, try deleting or archiving those emails to see if it resolves the issue.

✨ Wrapping Up

To resolve the 'Some messages could not be FETCHed (failure)' error in Thunderbird's Gmail IMAP connection, first verify and correct the IMAP server configuration. If this does not work, check mailbox permissions to ensure that the IMAP server has granted the necessary access to fetch messages from the mailbox.

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