0x800CCC90OfficeHigh
Error 0x800CCC90 — POP3 Server Error | Microsoft Office Fix
Microsoft 365Office 2021Office 2019Office 2016
What Does 0x800CCC90 Mean?
A general POP3 protocol error occurred. The POP3 mail server returned an unexpected or invalid response.
Real-World Causes
- 1Incorrect POP3 server address or port configuration
- 2POP3 server temporarily unavailable or undergoing maintenance
- 3Account locked due to multiple failed login attempts
- 4Corrupted email message on the server causing protocol error
Symptoms
- ⚠Cannot receive emails via POP3
- ⚠Error during email download
- ⚠Outlook hangs during receive operation
- ⚠Repeated authentication prompts
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DIY Fix
Beginner-friendly steps you can try at home
- 1Verify POP3 server address and port (usually port 995 with SSL)
- 2Log into webmail to confirm account is working
- 3Wait and retry — the server may be temporarily overloaded
- 4Check if your email provider still supports POP3
Advanced Fix
For experienced users and IT professionals
- 1Use webmail to delete any corrupted emails that may be blocking the download
- 2Recreate the Outlook mail profile
- 3Try switching from POP3 to IMAP for better reliability
- 4Check POP3 server logs if you have server access
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Frequently Asked Questions
Should I switch from POP3 to IMAP?
Yes, IMAP is generally recommended over POP3 for most users. IMAP keeps emails on the server, syncs across devices, and handles folders better. POP3 downloads and often deletes emails from the server.
What POP3 port should I use?
Use port 995 with SSL/TLS encryption (recommended). Port 110 is the unencrypted POP3 port but should be avoided for security reasons.
Related Error Codes
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.