Outlook: Error Message: A Connection Failure Has Occurred (Error -23012)

Email | Updated 2026
Quick Answer

Error -23012 indicates a network-level connection failure between Outlook and the mail server. Verify your internet connection is working, confirm the server is mail.yourdomain.com, and try switching to SSL ports (POP3: 995, IMAP: 993, SMTP: 465). If the issue persists, your IP may be temporarily blocked by the firewall.

For complete Outlook troubleshooting steps and all error codes, see our full guide:

Common Outlook Email Errors

Correct Email Settings

Most Outlook errors are caused by incorrect server settings. Use these values:

  • Incoming/Outgoing Server - mail.yourdomain.com
  • POP3 Port - 995 (SSL) or IMAP Port - 993 (SSL)
  • SMTP Port - 465 (SSL)
  • Username - your full email address
  • Authentication - enabled for outgoing, SPA disabled

For step-by-step setup: How to Set Up Email in Microsoft Outlook

This article has been consolidated into our Common Outlook Email Errors guide for easier reference.

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