0x800CCC0FOfficeHigh
Error 0x800CCC0F — Outlook Connection Dropped | Microsoft Office Fix
Microsoft 365Office 2021Office 2019Office 2016
What Does 0x800CCC0F Mean?
The connection to the mail server was dropped during communication. The server unexpectedly terminated the session.
Real-World Causes
- 1Unstable internet connection causing disconnections
- 2Mail server overloaded and dropping connections
- 3Antivirus scanning email traffic and interfering
- 4Large attachment causing timeout during transfer
Symptoms
- ⚠Send/Receive operation fails partway through
- ⚠Partial email synchronization
- ⚠Intermittent connectivity to mail server
- ⚠Error occurs mid-download of emails
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DIY Fix
Beginner-friendly steps you can try at home
- 1Check and stabilize your internet connection
- 2Reduce the size of email attachments
- 3Disable antivirus email scanning temporarily
- 4Increase the server timeout value in Outlook account settings
Advanced Fix
For experienced users and IT professionals
- 1Adjust Outlook server timeout: File > Account Settings > Change > More Settings > Advanced > Server Timeouts
- 2Check for corrupted emails on the server using webmail
- 3Create a new Outlook profile and reconfigure the account
- 4Update Outlook to the latest version with all patches
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Frequently Asked Questions
How do I increase Outlook's server timeout?
Go to File > Account Settings > select your account > Change > More Settings > Advanced tab. Move the Server Timeouts slider to the right (up to 10 minutes).
Could a large email cause this?
Yes. A very large email or attachment can cause the connection to timeout and drop. Try accessing your email via webmail and deleting any unusually large messages.
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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.