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0×800ccc0f "Your server has unexpectedly gone offline" error message when sending an SMTP email message


This problem can seem to come out of nowhere. One day everything is fine, the next day Microsoft Outlook is complaining about error 0×800ccc0f when trying to send emails.

It is essential that Microsoft products conflict with Microsoft products such as MS Window Firewall which blocks MS Outlook. Check if any of the following scenarios apply to you and follow the steps to fix the problem.

The following message is displayed every time Outlook starts:

"Task" Sync subscribed folders for [email protected]'reported error (0x800CC0F) Outlook cannot sync subscribed folders The TCP/IP connection was unexpectedly terminated by the server. If you continue to receive this message, please contact the server administrator.

How can this error be corrected?

Disable Windows firewall / anti-malware firewall


To disable Windows Firewall:

  1. Open Control Panel (Start > Control Panel).
  2. Open network connection
  3. Right-click the Internet connection you are using (GreenNet Switched, Wireless, or Local Area Network).
  4. Select "Properties" from the menu.
  5. Go to the “Security” tab and disable the firewall.

If the problem persists, you must manually add the POP servers. To do this, follow the steps below:

  1. Start Outlook.
  2. On the Tools menu, click Email Accounts.
  3. click View or edit existing email accounts, then click Next.
  4. In the Email Accounts dialog, click Add.
  5. click POP3, then click Next.
  6. Enter the correct information for your POP3 mail server, then click Next.
  7. click Finish.

Make sure you are connected to the Internet.

First of all, please make sure your computer send/receive data via the internet or not. For that:

Open a browser window and enter the URL of a web portal. When it opens, it means your computer is connected.
If this is not the case, you need to troubleshoot your network connectivity by right-clicking your Wi-Fi or Ethernet cable connection signal and clicking Troubleshoot from the context menu.

Start Outlook in safe mode

If you start Outlook in safe mode, disable add-ins and start Outlook with default settings only. If faulty plugins are the cause of the problem, this may fix the problem. For that:

Open search in the “Start” menu or enter outlook.exe /safe in the “Search” field and click OK. For Outlook 2003 and earlier versions, you need to enter it in the Run dialog box.

Microsoft has confirmed that this is an issue with the Microsoft products listed at the beginning of this post. This problem was first fixed in Microsoft Windows 2000 Service Pack 4.

RECOMMENDED: Click here to fix Windows errors and get the most out of your system performance