18 Solutions for Username and Password Not Accepted in Gmail SMTP

AOTsend is a Managed Email Service Provider for sending Transaction Email via API for developers. 99% Delivery, 98% Inbox rate. $0.28 per 1000 emails. Start for free. Pay as you go. Check Top 10 Advantages of Managed Email API

Gmail SMTP servers are widely used for sending emails programmatically. However, users often face issues where their username and password are not accepted. This can be frustrating, especially when you're trying to set up an automated email system. In this article, we'll explore 18 solutions to help you troubleshoot and resolve this common problem.

Solution 1: Check Your Credentials

First and foremost, double-check your Gmail username and password. Ensure there are no typos or mistakes. Sometimes, the simplest solution is the correct one.

Solution 2: Enable Less Secure Apps

Gmail, by default, might block less secure apps from accessing your account. You can change this setting by visiting your Google account's security settings and allowing less secure apps.

Solution 3: Use App-Specific Passwords

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

Solution 4: Check Your SMTP Settings

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

Solution 5: Update Your Software

If you're using an email client or a programming library to send emails, make sure it's up to date. Outdated software can cause compatibility issues.

Solution 6: Verify Your Account Isn't Blocked

Sometimes, Google might block an account if it detects unusual activity. Check your Google account status to ensure it's not been blocked or limited.

Solution 7: Clear Cookies and Cache

If you're accessing Gmail through a web browser, clearing cookies and cache can sometimes resolve login issues.

Solution 8: Disable Browser Extensions

Certain browser extensions might interfere with Gmail's login process. Try disabling them and see if it helps.

Solution 9: Check Your Firewall Settings

Ensure your firewall or antivirus software isn't blocking Gmail's SMTP ports.

【AOTsend Email API】：
AOTsend is a Transactional Email Service API Provider specializing in Managed Email Service. 99% Delivery, 98% Inbox Rate. $0.28 per 1000 Emails.
AOT means Always On Time for email delivery.

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

Solution 10: Test Your Connection

Use tools like Telnet or Putty to test your SMTP connection. This can help identify if the issue lies with your network or Gmail's servers.

Solution 11: Contact Your ISP

Sometimes, internet service providers (ISPs) might block certain ports. Contact your ISP to inquire about any potential blocks.

Solution 12: Review Gmail's Status Dashboard

Check Gmail's status dashboard to see if there are any known issues or outages that might be affecting your service.

Solution 13: Reset Your Password

If you suspect your account has been compromised, resetting your password is a good security measure.

Solution 14: Use OAuth 2.0 for Authentication

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

Solution 15: Check for Third-Party Access

Review any third-party apps or services that might be trying to access your Gmail account. Revoke access if necessary.

Solution 16: Enable IMAP in Gmail Settings

While IMAP is primarily for receiving emails, enabling it in your Gmail settings can sometimes resolve SMTP-related issues as well.

Solution 17: Try a Different Device or Network

To rule out local issues, try accessing Gmail SMTP from a different device or network.

Solution 18: Contact Google Support

If none of the above solutions work, it's time to reach out to Google Support for further assistance.

In conclusion, there are multiple potential reasons why your Gmail username and password might not be accepted for SMTP authentication. By following the solutions outlined in this article, you should be able to troubleshoot and resolve the issue. Remember, patience and careful troubleshooting are key to finding the root cause of the problem.

AOTsend adopts the decoupled architecture on email service design. Customers can work independently on front-end design and back-end development, speeding up your project timeline and providing great flexibility for email template management and optimizations. Check Top 10 Advantages of Managed Email API. 99% Delivery, 98% Inbox rate. $0.28 per 1000 emails. Start for free. Pay as you go.