I can’t send or receive email, Outlook Error 0x8004210B

Outlook Error 0x8004210B, can’t send or receive email

Common error message(s):

"0x8004210B "
“The operation timed out waiting for a response from the receiving (POP) server.”
“Sending and Receiving’ reported error (0x800CCC0B): ‘Unknown Error 0x800CCC0B’”


  1. You can’t send or receive email using a POP3 email account.

Recommended Troubleshooting steps:

I. Microsoft Office has a recommended Microsoft Fixit for this issue, to resolve the issue, you may download it from this link: Bing

  1. Modify and enable hotfix using registry keys. To do this, follow these steps:

a. Close MS Outlook.
b. Click Start, click Run, type “regedit” and then click OK. This will open the Registry Editor.
c. It is strongly advised to backup your Windows Registry prior to making changes to it. Follow the steps to backup your registry.
d. In Registry Editor, Click File, select Export, ensure that the correct file is located HKEY_CURRENT_USER\Software\Microsoft\Office\Outlook and click the registry key.
e. Name the file with your Current Time and Date, Click on Save, you may refer to image at this link: http://safe.mn/Uxc~

  1. Go back to the selected key,HKEY_CURRENT_USER\Software\Microsoft\Office\Outlook

a. Go to the Edit menu, select New and then click DWORD.
b. Type UseInetcommCS, and then press ENTER.
c. Right-click UseInetcommCS, and then click Modify.
d. In the Value data box, type 1, and then click OK.
e. On the File menu, click Exit to quit Registry Editor.
f. Restart your computer, and relaunch Outlook afterwards.
g. If issue persists, proceed in checking your security settings.

II. Check your security software settings, as it may be interfering with the ability of your email client, to connect to the POP3 Server. POP3 is the abbreviation for Post Office Protocol - a data format for delivery of emails across the Internet.

  1. For Comodo Internet Security follow the steps below:
    a. Ensure that your POP Server settings are allowed. Go to Advanced Settings, Firewall Settings, and then Port Sets (Comodo Internet Security Port Sets, Firewall Protection | Internet Security v7.0)
    b. Your computer sends and receives data to other computers and to the Internet through a port. There are over 65,000 numbered ports on every computer - with certain ports being traditionally reserved for certain services. For example, your machine almost definitely connects to Internet using port 80 and port 443. By default most e-mail client software connects to your email provider’s mail server through port 25.
    c. Additionaly, you may check if your email client’s executable has to be added unto your Antivirus’ Exclusion Applications list (Exclude Files / Applications to Scan, PC Antivirus | Internet Security v7.0)

  2. For users of Symantec products you may refer to this link: Endpoint Protection Small Business Edition - Symantec Enterprise .

  3. For users of McAfee products you may refer to this link: http://service.mcafee.com/faqdocument.aspx?id=TS100813

  4. For users of Trend Micro products, you may refer to this link: Support | Trend Micro Help Center

  5. You may also refer to the manufacturer’s website/documentation on how to configure the permission/exemptions list of ports and applications.

III. Contact GeekBuddy Support
a. Via phone, you can reach us through 855-301-4475 or 888-351-8017.
b. Via the GeekBuddy Chat Application, indicate your issue as “Outlook Error 0x8004210B”, “Outlook Error 0x8004210A“, “Outlook Error 0x800CCC0B“ or simply as “POP3 Errors/can’t send and receive e-mail”