Task ‘server name – Sending and Receiving’ reported error (0x800ccc0f): ‘The connection to the server was interrupted. If this problem continues, contact the server administrator or Internet service provider (ISP). The server responded: ? K’
Usually caused by Antivirus software scanning email, but antispam scanners may cause Outlook to return this error as well. Disable the email scanning or increase the timeout setting.
Also, make sure your firewall is allowing the scanner software to connect to the Internet.