How to Fix Thunderbird SMTP Timeout for Hotmail Accounts
Question details
Thunderbird times out when attempting to send emails using a Hotmail or Outlook account via smtp.office365.com.
- Product
- Mozilla Thunderbird
- Device & OS
- not provided
- Scenario
- Sending outgoing emails from a Hotmail or Outlook.com account through the Thunderbird client.
- Observed behavior
- The email client experiences a timeout error and fails to send outgoing messages, even when using standard port 587, STARTTLS, and OAuth2 configurations.
Before making changes, verify that your internet connection is stable and check the Microsoft Office 365 service status page to ensure there are no ongoing server outages affecting Outlook.com or Hotmail outgoing servers.
Verify SMTP Configuration and Re-add the Account
Ensure your outgoing server settings strictly follow Microsoft's requirements, and refresh the OAuth2 authentication token by re-adding the account.
Microsoft has discontinued Basic Authentication. If your Thunderbird account is retaining old login tokens or has minor SMTP misconfigurations, it will silently time out instead of successfully connecting to smtp.office365.com.
Go to Tools or the application menu, select 'Account Settings', and click on 'Outgoing Server (SMTP)' located at the bottom of the left pane.
Ensure the Server Name is exactly 'smtp.office365.com', the Port is set to '587', the Connection security is 'STARTTLS', and the Authentication method is 'OAuth2'.
Verify that your full Hotmail or Outlook email address (e.g., yourname@hotmail.com) is entered in the Username field, rather than just the prefix.
If settings are correct but the timeout continues, remove the affected Hotmail account and SMTP entry from Account Settings. Restart Thunderbird and add the account again to trigger a fresh Microsoft OAuth2 browser prompt.
Temporarily Disable Antivirus Email Scanning
Security software or third-party antivirus programs can intercept and block SMTP ports, interfering with OAuth2 authentication.
Test on a Different Network Connection
Your local network firewall, VPN, or Internet Service Provider (ISP) might be blocking outgoing SMTP traffic on port 587.
Looking for a Lightweight Alternative to Microsoft Office?
While troubleshooting your Hotmail and Outlook accounts in Thunderbird, consider upgrading your daily document productivity tools. WPS Office is a free, lightweight, and complete office suite that provides exceptional compatibility with all Microsoft Office document formats.
Frequently Asked Questions
Why does OAuth2 authentication fail on Thunderbird for Hotmail?
OAuth2 authentication can fail if your browser cookies are disabled within Thunderbird, if there's an outdated saved token, or if security software is intercepting the secure connection. Removing the account and re-adding it usually prompts a fresh Microsoft login screen to generate a new valid token.
Can I use 'Normal password' instead of OAuth2 for Hotmail?
No. Microsoft has deprecated basic authentication (Normal password) for its email services. You must configure Thunderbird to use OAuth2 for all Hotmail, Live, and Outlook.com accounts to ensure secure login and prevent connection timeouts.
How do I check Thunderbird error logs for SMTP timeouts?
You can open the Error Console in Thunderbird by pressing Ctrl+Shift+J on Windows/Linux or Cmd+Shift+J on Mac. This console displays background errors, including detailed SMTP connection failures, which can help pinpoint the exact cause of a timeout.
Will port 465 work instead of 587 for Outlook.com SMTP?
Microsoft strictly recommends using port 587 with STARTTLS for smtp.office365.com. While port 465 with SSL/TLS is used by many other email providers, Outlook.com environments typically require port 587. Using port 465 for Hotmail usually results in an immediate connection failure or timeout.
