How do I fix: Using a Third-Party SMTP Service?

Step 1: Consider using a third-party SMTP service like SendGrid, Mailgun, or Amazon SES, which offer more relaxed authentication requirements.Step 2: Create an account with the chosen service and obtain your SMTP credentials (e.g., username and password).

Software⏱️ 3 min read📅 2026-06-03

How to Fix: Gmail Error :The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.5.1 Authentication Required

Q: Best Solutions to Fix It Enabling Less Secure Apps in Your Gmail Account?

Step 1: Open your Gmail account and navigate to the 'Security' tab.Step 2: Scroll down to the 'Less secure app access' section and toggle the switch to enable it.Step 3: Save changes and try sending an email again. Note that enabling this feature may compromise your account security, so use it with

Learn how to fix: Gmail Error :The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.5.1 Authentication Required.

Quick Answer: Try checking your system settings or restarting.

📋 Table of Contents

💡 Why You Are Getting This Error
✅ Best Solutions to Fix It
🎯 Final Words

Gmail Error: The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.5.1 Authentication Required

This error affects users who are trying to send emails using Gmail's SMTP server, but it has been resolved in your local machine. However, on your production server, you're encountering this issue, which can be frustrating and disrupt your email communication.

💡 Why You Are Getting This Error

The primary reason for this error is that Gmail has implemented stricter security measures to protect user accounts. To send emails using Gmail's SMTP server, you need to use a secure connection (TLS or SSL) and authenticate the client (i.e., provide your username and password).
Alternatively, if you're using an application or service that doesn't support authentication or uses outdated credentials, it may also cause this error.

✅ Best Solutions to Fix It

Enabling Less Secure Apps in Your Gmail Account

Step 1: Open your Gmail account and navigate to the 'Security' tab.
Step 2: Scroll down to the 'Less secure app access' section and toggle the switch to enable it.
Step 3: Save changes and try sending an email again. Note that enabling this feature may compromise your account security, so use it with caution.

Using a Third-Party SMTP Service

Step 1: Consider using a third-party SMTP service like SendGrid, Mailgun, or Amazon SES, which offer more relaxed authentication requirements.
Step 2: Create an account with the chosen service and obtain your SMTP credentials (e.g., username and password).

🎯 Final Words

To resolve this issue on your production server, you can try enabling Less Secure Apps in your Gmail account or use a third-party SMTP service. If you're still experiencing issues, ensure that your application or service is properly configured to authenticate with the Gmail SMTP server.

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