How to Fix Sending reported error 0x8004210B in Outlook

It usually occurs when SMTP port 25 or 587 is blocked by either your ISP or firewall in your local machine. You may check it by simply telnet’ing on port 25 on your domain. You may experience when you receive or send an email message in Outlook. This guide will show you How to Fix Sending reported error 0x8004210B in Outlook.

Step 1: Make sure that you are connected to the Internet and able to telnet SMTP port number.

To do this, follow these steps:

  • Start an Internet browser. Or ping the google.com; ping www.google.com. You should get reply as below if the computer connected with Internet.

How to Fix Sending reported error 0x8004210B in Outlook.

Telnet’ing the SMTP port.

  • Hold down Windows Key and hit on R key .This will bring up the Run Windows. Type CMD and hit enter.
  • Type command as telnet smtp.servername.com 25.
  • Example: If you have a google domain account. The telnet command should be: telnet smtp.gmail.com 25

C:\Users\TS-01\Desktop\telnet.JPG

  • You will get the reply as below If not customer to contact ISP (Internet Service Provider).

Step 2: Make sure that your Outlook email account settings are correct.

  • Click on the “Account Settings” under the “Tools” menu. How to Fix Sending reported error 0x8004210B in Outlook.
  • Click on the “Email” and make a double click on the email address by which you are not able to send emails.
  • Through double click other pop-up window will appear, now click on “More Settings buttons.
  • Go to the Outgoing Server tab and select the “My outgoing server (SMTP) requires authentication” checkbox.

How to Fix Sending reported error 0x8004210B in Outlook

  • Change Outgoing Server (SMTP) Port number from 25 to 587.

How to Fix Sending reported error 0x8004210B in Outlook

Step 3: Disable or uninstall anti-virus.

Check your antivirus manufacturer’s website for additional suggestions or Disable the antivirus software. And Disable the firewall in router. If you found outlook is working fine after disable the antivirus software, recommend you to uninstall the same using their removal tool and reinstall it.

List of manual antivirus uninstallers:

Click the link associated with the antivirus software currently installed on your system and follow the prompts or instructions on the website. After uninstall, reboot the computer.

Refer below links to disable, uninstall or reinstall antivirus software on your computer

Conclusion:

We recommend that you contact your Internet service provider (ISP) for information about the exact incoming and outgoing mail server names and settings that you should use when you configure your Internet email account in Outlook. Hope you learned How to Fix Sending reported error 0x8004210B in Outlook and it resolved issues. If not you need to contact your email providers or Internet service provider. Meanwhile ask your queries in comments or Forum.