18 Solutions for Gmail SMTP Username and Password Not Accepted Issues

Hello everyone, I’m Kent, the website admin. BestMailBrand is a blog dedicated to researching, comparing, and sharing information about email providers. Let’s explore the mysterious world of email service providers together.

When setting up an email client or a website to send emails using Gmail's SMTP server, you may encounter issues where your Gmail SMTP username and password are not accepted. This can be frustrating, especially when you're sure you've entered the correct credentials.幸运的是, there are multiple solutions you can try to resolve these issues. Here are 18 potential fixes:

1. Double-Check Your Credentials

The first and foremost step is to ensure that you've entered the correct username and password. Remember, your Gmail username is your full Gmail address, and the password is case-sensitive.

2. Enable Less Secure Apps

Gmail, by default, might block sign-in attempts from apps it considers less secure. You can change this by allowing less secure apps in your Gmail account settings.

3. Use App-Specific Passwords

If you have two-step verification enabled on your Google account, you'll need to generate and use an app-specific password for SMTP authentication.

4. Check Your SMTP Settings

Ensure that your SMTP server settings are correct. For Gmail, the SMTP server is smtp.gmail.com, and the port is usually 587 for TLS/STARTTLS or 465 for SSL.

5. Update Your Email Client or Plugin

Sometimes, outdated email clients or plugins can cause authentication issues. Make sure you're using the latest version.

6. Disable Firewall or Antivirus

Your firewall or antivirus software might be blocking the SMTP connection. Try disabling them temporarily to see if it resolves the issue.

7. Check Your Internet Connection

A stable internet connection is crucial for SMTP authentication. If your connection is unstable, it can cause authentication failures.

8. Clear Cookies and Cache

Sometimes, clearing your browser's cookies and cache can resolve login issues.

9. Try a Different Browser or Device

If you're trying to set up SMTP through a web interface, try using a different browser or device to see if the problem persists.

10. Contact Your ISP

Certain ISPs might block SMTP ports. Contacting your ISP can help you determine if this is the case and how to resolve it.

11. Check Gmail's Status

Visit the Gmail status dashboard to check if there are any service disruptions that might be affecting SMTP.

12. Review Third-Party App Permissions

If you're using a third-party app to send emails, ensure it has the necessary permissions to access your Gmail account.

13. Reset Your Gmail Password

If you suspect your account has been compromised, resetting your Gmail password might help.

14. Disable Two-Step Verification

While two-step verification enhances security, it can sometimes cause authentication issues. You can temporarily disable it to troubleshoot.

15. Use OAuth 2.0 for Authentication

AOTsend is a Managed Email Service API for transactional email delivery. 99% Delivery, 98% Inbox Rate.
Start for Free. Get Your Free Quotas. Pay As You Go. $0.28 per 1000 Emails.

You might be interested in:
Why did we start the AOTsend project, Brand Story?
What is a Managed Email API, How it Works?
Best 24+ Email Marketing Service (Price, Pros&Cons Comparison)
Best 25+ Email Marketing Platforms (Authority,Keywords&Traffic Comparison)

For more secure and reliable authentication, consider using OAuth 2.0 instead of traditional username and password authentication.

16. Check for Gmail Account Restrictions

Ensure your Gmail account isn't restricted due to suspicious activity or policy violations.

17. Seek Help from the Gmail Help Forum

The Gmail Help Forum is a great resource for finding solutions to common problems.

18. Contact Google Support

If none of the above solutions work, you can contact Google Support for further assistance.

Remember, when dealing with email authentication issues, patience and careful troubleshooting are key. By following these steps, you should be able to resolve most Gmail SMTP username and password not accepted issues.

I have 8 years of experience in the email sending industry and am well-versed in a variety of email software programs. Thank you for reading my website. Please feel free to contact me for any business inquiries.