13 Troubleshooting Steps for Office 365 SMTP Authentication Failures

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 it comes to email communication, Office 365 has become a popular choice for businesses and individuals alike. However, even the most reliable services can encounter issues, and SMTP authentication failures are among the most common problems users face. If you're struggling with SMTP authentication failures in Office 365, here are 13 troubleshooting steps to help you resolve the issue.

1. Check Your Credentials

First and foremost, verify that you are using the correct username and password for SMTP authentication. Any typo or misremembered credential can cause authentication to fail.

2. Review SMTP Settings

Ensure that your SMTP server settings are configured correctly. This includes the SMTP server address, port number, and encryption method. For Office 365, the typical SMTP server setting is smtp.office365.com using port 587 with TLS encryption.

3. Update Your Email Client

If you're using an email client like Outlook, Thunderbird, or any other third-party application, make sure it's updated to the latest version. Outdated clients may not support the latest authentication methods.

4. Check Firewall and Router Settings

Sometimes, firewall or router settings can block SMTP connections. Ensure that your firewall or router allows outbound connections on the SMTP port you're trying to use.

5. Disable Antivirus or Firewall Temporarily

In some cases, antivirus software or firewalls can interfere with SMTP authentication. Try temporarily disabling them to see if it resolves the issue.

6. Multi-Factor Authentication (MFA)

If your Office 365 account has MFA enabled, you might need to create an app password specifically for SMTP 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)

7. Check for Service Outages

Visit the Office 365 Service Health Dashboard to check if there are any known issues or outages that might be affecting SMTP services.

8. DNS Settings

Verify that your DNS settings are correct and that your domain is properly pointed to Office 365. Incorrect DNS records can cause authentication issues.

9. Review Connector Settings

If you're using a connector to route emails, double-check its configuration to ensure it's set up correctly.

10. License Verification

Confirm that your Office 365 license is active and includes the necessary features for SMTP relay.

11. Server Connectivity

Use tools like ping or traceroute to check the connectivity between your server and the Office 365 SMTP server.

12. View Logs and Error Messages

Examine any error logs or messages provided by your email client or server for additional clues to the problem.

13. Contact Support

If all else fails, don't hesitate to contact Office 365 support for further assistance.

By following these 13 troubleshooting steps for Office 365 SMTP authentication failures, you should be able to pinpoint and resolve most issues. Remember to always keep your systems and applications up to date, and regularly monitor your account and network settings to prevent future problems. With these tips, you can ensure smooth and uninterrupted email communication for your business or personal needs.

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.