Perfect Method to fix Error 0x8004210b Outlook 2016

In this digital world, some Outlook users encounter Microsoft error “0x8004210b Outlook 2016”. But they are facing trouble when trying to fix the error. So, in this blog,  we will discuss the different methods to fix the error and the possible causes of the errors. 

Error 08004210b of Outlook

Microsoft Outlook allows its users to access old emails in a lack of Internet connectivity. In the active Internet connection, users can download whole emails and also execute the process of send and receive. Sometimes due to improper email configuration or many other reasons, users face Outlook error 0x8004210b. This error is encountered when any of your ISP or firewall in your local machine blocks the SMTP port 25 or 587. You may see it with telnet on port 25 on your domain. 

Let’s discuss the solutions and possible reasons due to which you face this error. 

Why do Microsoft users encounter Error “0x8004210b Outlook 2016”?

There may be several reasons for this error, Let’s see some of the most common reasons:

1. Email Blockage

Due to the stuck messages in the outbox, the emails get blocked while sending and result in the error.

2. Virus or malicious attack : 

Virus attack is the most common reason behind a Window or file corruption. And it also results in Microsoft Outlook error Message 0x8004210b.

3. Unfinished Software installation

If software installation is not completed properly then it also becomes the reason for the error.

4. Damaged or Corrupt System files

Any Damaged or corrupt system results in the Outlook sending error 0x8004210b. 

So here we discussed the different possible reasons behind the error “08004210b Outlook 2016”. Now, let’s discuss the solution to fix the error. 

Perfect Solution to Troubleshoot the Error 0x8004210b:

There are several other ways to fix the error, but here in this blog, we will discuss the most perfect and easy solution to the Microsoft Outlook Error message 0x8004210b. Let’s discuss them as below:

Solution 1. Execute complete Scanning of Your System using Antivirus:

As we discussed above the error occurs due to the virus attack so you can execute a complete scanning your system. And by doing so you will easily get rid of any malware or viruses with an antivirus program. 

Solution 2. Execute an Update:

Sometimes Outlook encounters this because of the outdated drivers or Windows. Getting to the specific driver that gives the error is very difficult. So you need to update the driver at regular intervals, this will help you to prevent the Outlook error 0x8004210B.

Along with the drivers, ensure regular updates on your Windows software. 

Go to Start >> All Programs >>Windows Update. Then tap on Change Settings and Press on Automatic. This will update the windows automatically whenever it requires any update.

Solution 3.  Repair the Registry Entries 

Follow the below-given steps carefully in order to get rid of the error 0x8004210b :

  • Reach the  Start button on your system and type “Command” in the search box.
  • Press Ctrl+Shift+Enter. After this, a dialog box will appear, press Yes.
  • Now, type “regedit” on the available black box and hit on Enter.
  • Choose the error 0x8004210B associated key in the Registry editor you need to take back up.
  • Tap on File >>Export
  • Choose the folder as per your need and save the Outlook backup key in that folder.
  • Go to the File Name box, provide the name of your backup file.
  • Now in the Export Range box, ensure that you choose the option “Selected Branch”. Then press on Save
  • Now you have a backup available of your MS Outlook related registry entry. You can edit your registry manually.

Note: It is not recommended to edit the registry manually as there is a high probability of damage to your system. 

Solution 4.  Uninstall and Reinstall MS Outlook Application:

Sometimes the Outlook error also occurs due to Microsoft Corporation Program. For this you need to uninstall and reinstall the Outlook application, this will help you to fix the Outlook error  0x8004210b. All you need to do is view the Control Panel and uninstall the application. After complete uninstallation, again reinstall the MS Outlook. 

So, here we discussed the most perfect solution to troubleshoot the error 0x8004210b. But somehow if the same error still persists then it means that your Outlook is severely corrupt. Then in such a case, you can use a Cigati PST Recovery Tool. The tool is an extensive utility that can perform Outlook data recovery easily and safely. The tool can easily repair or restore the corrupt PST due to different reasons, and also restore the Outlook mailbox into a new PST file. 


Here in this blog, we discussed the different solutions to fix the error “0x8004210b Outlook 2016”. Hope after reading this blog, you will successfully troubleshoot your problem and get rid of the error easily.

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