Software⏱️ 3 min read📅 2026-06-19

How to Fix: Thunderbird can't send emails - SMTP error

Thunderbird email sending issue with Outlook/Hotmail account

Quick Answer: Check if two-factor authentication is enabled on the Outlook/Hotmail account and disable it to resolve the issue.

📋 Table of Contents

  1. ⚠️ Common Causes
  2. ✅ Best Solutions to Fix It
  3. 🎯 Final Words

Thunderbird users are experiencing an issue where they cannot send emails using their Outlook/Hotmail accounts. The error message 'Login to server smtp.live.com failed.' is displayed, causing frustration for those who have successfully received emails on these same accounts.

This problem affects Thunderbird users who rely on their email clients to send messages, and it's essential to resolve this issue as soon as possible to avoid any disruptions in communication.

⚠️ Common Causes

  • The primary reason for this error is that the STARTTLS encryption method used by the SMTP server may not be compatible with Thunderbird. This can lead to a failure in establishing a secure connection, resulting in the 'Login to server smtp.live.com failed.' error message.
  • Another possible cause could be that the port number specified (587) might not be correct or is blocked by the firewall. Additionally, if the SMTP server settings are incorrect or outdated, it can also lead to this issue.

✅ Best Solutions to Fix It

Check and Update Thunderbird's SMTP Server Settings

  1. Step 1: Open Thunderbird and go to 'Tools' > 'Account Settings'. Select the email account you're trying to send emails from and click on the 'Edit Server Settings' button.
  2. Step 2: In the 'Server Settings' window, ensure that the 'Server Name' is set to smtp.live.com, the 'Port' is set to 587, and the 'Authentication' is set to Normal password. Make sure the 'Security' option is set to STARTTLS.
  3. Step 3: Click 'OK' to save the changes and try sending an email again.

Check Firewall Settings and Port Configuration

  1. Step 1: Open your firewall settings (Windows: Windows Defender Firewall, macOS: System Preferences > Security & Privacy > Firewalls) and ensure that the port 587 is not blocked.
  2. Step 2: If you're using a third-party firewall or antivirus software, check their configuration to see if it's interfering with Thunderbird's email sending functionality. You might need to add an exception for the SMTP server settings.

🎯 Final Words

To resolve the 'Login to server smtp.live.com failed.' error in Thunderbird, try updating your SMTP server settings or checking your firewall and port configuration. If these steps don't work, consider reaching out to the SMTP server provider (in this case, Microsoft) for further assistance.

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