5.7.57 client not authenticated to send mail. error: 535 5.7.139
A classic error!
The error message "5.7.57 client not authenticated to send mail. error: 535 5.7.139" typically indicates that your email client or server is trying to send an email, but the SMTP server (the server that handles email sending) is refusing to accept the email because the client is not authenticated.
Here are a few possible reasons for this error:
- SMTP Authentication required: The SMTP server requires authentication (e.g., username and password) to send emails. Your email client or server is not providing the necessary authentication credentials.
- Incorrect SMTP server settings: Double-check your email client or server settings to ensure that the SMTP server address, port, username, and password are correct.
- Authentication method mismatch: The SMTP server may be configured to use a specific authentication method (e.g., PLAIN, LOGIN, or CRAM-MD5), but your email client or server is using a different method.
- Firewall or network issues: Firewalls or network issues may be blocking the connection to the SMTP server.
To resolve this issue, you can try the following:
- Check your email client or server settings: Verify that your email client or server is configured to use the correct SMTP server settings, including the server address, port, username, and password.
- Enable SMTP authentication: If your email client or server is not already configured to use SMTP authentication, enable it and provide the necessary authentication credentials.
- Use a different SMTP server: If you're using a third-party SMTP server, try using a different one to see if the issue persists.
- Check your firewall or network settings: Ensure that your firewall or network settings are not blocking the connection to the SMTP server.
- Contact your email provider or IT administrator: If you're still having trouble, contact your email provider or IT administrator for assistance, as they may be able to provide more specific guidance or troubleshoot the issue.