How to Fix 0x800CCC0B Outlook Error

The 0x800CCC0B Outlook error typically appears when Outlook fails to send or receive emails through an SMTP server. When this error occurs, Outlook may display messages such as “Server error 0x800CCC0B” or indicate that the SMTP connection failed. As a result, outgoing emails may remain stuck in the Outbox.

This error is usually caused by incorrect SMTP settings, authentication problems, firewall restrictions, damaged Outlook profiles, or corrupted account configurations. In many cases, fixing the email server settings or repairing the Outlook profile resolves the issue.

If you are encountering the 0x800CCC0B error in Outlook, follow the troubleshooting steps below.

How to Fix 0x800CCC0B Outlook Error

Work through each solution in order. After completing a step, try sending an email to check if the problem is resolved.

1. Verify SMTP Server Settings

Incorrect outgoing mail settings are one of the most common causes.

1. Open Outlook.
2. Click File.
3. Select Account Settings and choose Account Settings again.
4. Select your email account and click Change.
5. Verify the Outgoing mail server (SMTP) address.
6. Ensure the correct port number and encryption method are configured.
7. Click Next and test the account settings.

Your email provider’s official documentation should list the correct SMTP settings.

2. Enable SMTP Authentication

Many mail servers require authentication before sending emails.

1. Open Outlook.
2. Go to File > Account Settings > Account Settings.
3. Select your email account and click Change.
4. Click More Settings.
5. Go to the Outgoing Server tab.
6. Check My outgoing server (SMTP) requires authentication.
7. Select Use same settings as my incoming mail server.
8. Click OK and save the settings.

After enabling authentication, test email sending again.

3. Check SMTP Port and Encryption

Incorrect port settings may cause connection failures.

1. Open Outlook.
2. Go to File > Account Settings.
3. Select your email account and click Change.
4. Click More Settings.
5. Go to the Advanced tab.
6. Verify SMTP settings, such as:
   • Port 587 (TLS)
   • Port 465 (SSL)
7. Click OK and restart Outlook.

Use the recommended settings provided by your email provider.

4. Disable Antivirus Email Scanning Temporarily

Some antivirus programs block SMTP communication.

1. Open your antivirus software.
2. Locate Email scanning or SMTP protection settings.
3. Temporarily disable email scanning.
4. Restart Outlook and send a test email.

If the email sends successfully, configure antivirus exceptions.

5. Check Windows Firewall Settings

Firewall rules may block Outlook from connecting to the SMTP server.

1. Press Windows + R.
2. Type: control firewall.cpl
3. Press Enter.
4. Click Allow an app or feature through Windows Defender Firewall.
5. Ensure Microsoft Outlook is allowed on both Private and Public networks.
6. Restart Outlook.

This ensures Outlook can communicate with mail servers.

6. Repair Outlook Data File

Corrupted Outlook data files may cause send/receive errors.

1. Close Outlook.
2. Locate the SCANPST.exe tool on your system.
3. Run the tool.
4. Browse and select your .PST file.
5. Click Start to scan for errors.
6. Repair any detected issues.

After repairing the file, reopen Outlook and test email sending.

7. Create a New Outlook Profile

A damaged Outlook profile can cause SMTP errors.

1. Press Windows + R.
2. Type: control mlcfg32.cpl
3. Press Enter.
4. Click Show Profiles.
5. Select Add.
6. Create a new profile and configure your email account.
7. Set the new profile as default.

After creating a new profile, try sending an email again.

8. Update Microsoft Office

Outdated Outlook versions may contain bugs.

1. Open Outlook.
2. Click File > Office Account.
3. Click Update Options.
4. Select Update Now.
5. Restart Outlook after the update completes.

Updates often fix connection issues.

Conclusion

The 0x800CCC0B Outlook error usually occurs when Outlook cannot communicate with the SMTP server due to incorrect settings, authentication issues, firewall restrictions, or corrupted profiles. In most cases, verifying SMTP settings and enabling outgoing server authentication resolves the problem quickly.

By following the troubleshooting steps above, you should be able to fix the error and restore normal email sending functionality in Outlook. If the issue persists, contacting your email provider to confirm server settings may help identify the underlying cause.