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0x800CCC67OfficeHigh

Error 0x800CCC67 — SMTP Server Error | Microsoft Office Fix

Microsoft 365Office 2021Office 2019Office 2016

What Does 0x800CCC67 Mean?

The SMTP server returned an unknown or unexpected error during the email sending process.

Real-World Causes

  1. 1SMTP server rejecting the email due to policy
  2. 2Sender address not authorized on the SMTP server
  3. 3Email flagged as spam by the sending server
  4. 4SMTP server misconfiguration or temporary error

Symptoms

  • ⚠Cannot send emails from Outlook
  • ⚠Emails remain in Outbox after send attempt
  • ⚠Error message about SMTP server rejection
  • ⚠Intermittent sending failures

DIY Fix

Beginner-friendly steps you can try at home

  1. 1Verify your sending email address matches the authenticated account
  2. 2Check if the recipient address is valid and not blocked
  3. 3Try sending a simple text email without attachments
  4. 4Verify SMTP authentication settings are enabled

Advanced Fix

For experienced users and IT professionals

  1. 1Enable SMTP logging to capture detailed server responses
  2. 2Check if the SMTP server requires specific authentication methods
  3. 3Test SMTP connectivity and commands using telnet
  4. 4Contact email provider to check for server-side blocks or restrictions

Frequently Asked Questions

What SMTP authentication should I use?
Most providers require SMTP authentication (SMTP AUTH). In Outlook, go to account settings > More Settings > Outgoing Server tab, and check 'My outgoing server requires authentication'. Use the same credentials as your incoming server.
Why can I receive but not send?
Incoming (POP3/IMAP) and outgoing (SMTP) use different servers. Your SMTP settings may be wrong, the SMTP server may be blocking you, or your ISP may be blocking the SMTP port. Check outgoing server settings specifically.

Related Error Codes

0x800CCC0EOutlook Connection Failed0x80042109Outlook Sending Timeout0x800CCC0FOutlook Connection Dropped

About the Author

Windows Troubleshooting Team

Verified against official Microsoft documentation and real-world diagnostic data. Error behavior confirmed across Windows 10, Windows 11, and Windows Server.