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Fix 'SMTP could not authenticate' error


Last updated on Sep 18, 2023

Troubleshooting SMTP Authentication Issues: Resolving 'Could Not Authenticate' Error

When attempting to configure your email account using the SMTP method, you might encounter a common and frustrating error message: "SMTP Error: Could not authenticate".

In this guide, we'll explore the various reasons behind this error and provide solutions to help you overcome it, ensuring a seamless email setup process.

1. Incorrect Email Credentials:

  • The Email Address and Username: Ensure that your email address and username match. Most of the time, they should be identical.

  • Password Compatibility: Use the same password you utilize for logging into your email inbox.

    Please do remember some providers like Gmail and Yahoo, requires you to use "App Password" instead of login password.

2. Incorrect SMTP Settings:

  • Verify SMTP Details: Confirm the accuracy of your SMTP server address and TLS / SSL Port number. Reach out to your email service provider for the correct SMTP settings if needed.

Common SSL Port for SMTP is 465

Common TLS Port for SMTP is 567

Alternative TLS Port used for SMTP commonly is 2525

3. Multi-Factor Authentication Enabled:

4. SMTP Connection Disabled by Your Email Service Provider:

  • Rare Occurrence: While uncommon, there are instances where email service providers disable the SMTP connection method. If you suspect this is the case, contact your email service provider to have SMTP enabled, ensuring you can use it for your email configuration needs.


SMTP authentication issues, particularly the "Could not authenticate" error, can be frustrating. However, by following the steps outlined in this guide, you can troubleshoot and resolve these problems efficiently.

Whether it's correcting your credentials, verifying SMTP settings, dealing with multi-factor authentication, or addressing provider-related issues, you now have the tools to overcome this common SMTP error and streamline your email setup process.