While using Outlook, if the SMTP-based email send / receive operation fails, users might see the following message:
"Sending / Receiving reported error (0x800CCC0F): The connection to the server was interrupted"
This error can arise without warning or any prior symptoms and hence can be very startling. To resolve it, you need to find the exact cause behind it and eliminate it completely.
Check Your Internet Connection
It might just be the case that your internet connection is down. So, check that websites are opening in your browser. If not, the issue is obviously due to a connection error. Rebooting your router might fix the connection.
Switch Off Anti-virus Software
Anti-virus software that scans emails can hamper Outlook’s incoming and outgoing emails. As such, disabling third-party anti-virus utilities might fix Outlook error 0x800ccc0f. You can temporarily remove your anti-virus software from the Windows startup and then restart the OS as follows.
-Right-click the Windows 10 taskbar and select Task Manager.
-Now select your anti-virus utility and press the Disable button.
-The anti-virus software will no longer start when you reboot Windows.
Switch Off the Windows Firewall
The Windows Firewall is another thing that can block MS Outlook. So switching the firewall off is another feasible resolution for Outlook error 0x800ccc0f. This is how you can configure the Windows Firewall settings in Windows 10.
-Click the Cortana button on the taskbar to open that app.
-Input the keyword ‘Windows Firewall’ in Cortana’s search box, and then select to open Windows Defender Firewall.
Click Turn Windows Firewall on or off to open the options shown directly below.
Select both the Turn off Windows Defender Firewall options there, and then press the OK button.
Clear up suspicious emails from Outlook and Outlook Outbox:
Sometimes, suspicious emails or emails with un-trusted attachments might be the real reason behind this error. If you think there are such emails within your Outlook inbox, delete them immediately. Also, if your Outlook outbox is overcrowded, clear it up (only the Outbox).
Increase the Server Timeouts Setting in Outlook:
Outlook includes a Server Timeouts bar that can fix interrupted connections when you drag it to a longer setting. As such, that is another option worth noting for fixing the Outlook error 0x800ccc0f. This is how you can increase the Server Timeouts setting in Outlook 2010.
-First, open the Outlook software; and then select the File tab.
-Press the Account Settings button and click Account Settings to open the E-mail Accounts window.
-Then press the Change > More Settings buttons to open the E-Mail Settings window.
-Click the Advanced tab, and then can drag the Sever Timeouts bar to the far right.
-Press the OK button to close the window.
Run Outlook in Safe Mode:
Outlook has a Safe Mode that can resolve numerous email error messages. The Safe Mode launches Outlook without any add-ins to ensure that they don’t conflict with the software in any way. You can open Outlook in Safe Mode as follows.
-Open the Win + X menu by pressing the Win key + X hotkey.
-Then click Run on the Win + X menu to open its window.
-Enter ‘Outlook /safe’ in Run’s text box and press the OK button.
A Choose Profiles window will then open. Press the OK button on that window.
Repair Outlook PST Files:
Error 0x800ccc0f can also be due to a corrupted Outlook data PST file. Outlook includes its very own Inbox Repair tool with which you can fix data files.