Resolve Outlook error 0x8004210b: Proven Methods

Common Reasons for Sending Reported Error 0x8004210b in Outlook

There can be several reasons for this issue:

• If your internet connection is weak or keeps disconnecting, Outlook may fail to communicate with the mail server.
• Wrong outgoing mail server details (server name, port number, or encryption type) can cause connection failure.
• Sometimes antivirus software scans outgoing emails and blocks the connection.
• A damaged Outlook profile can also cause sending errors.
• Moreover, if your Outlook data file (PST) is damaged, it may interfere with sending or receiving emails.

How to Fix Outlook Error 0x8004210B

Below are some practical solutions you can try to resolve this error. Start with the basic manual methods, and if the problem continues, you may consider using a professional repair tool.

Method 01: Check Your Internet Connection

1. Firstly, open a browser and test your internet.
2. Now, restart your router if needed.
3. Try sending the email again.
4. If your connection is unstable, fix that first.

Method 02: Verify Outgoing Server (SMTP) Settings

1. Primarily, open Outlook.
2. Then, go to File → Account Settings → Account Settings.
3. After that, select your email account and click Change.
4. Further, click More Settings → Outgoing Server.
5. Make sure: “My outgoing server (SMTP) requires authentication” is checked.
6. Check the Advanced tab: 
   • Confirm the correct SMTP port number (usually 587 or 465).
   • Verify encryption type (TLS or SSL as required by your provider).
7. In the end, click OK and test the account.

Method 03: Increase Server Timeout Settings to Resolve the Outlook Error 0x8004210b

If the server is slow, increasing the timeout may help.

1. Afterwards, go to Account Settings.
2. Next, click Change → More Settings.
3. Then, open the Advanced tab.
4. Increase the Server Timeout slider to a higher value.
5. Lastly, click OK and restart Outlook.

Method 04: Disable Antivirus Email Scanning (Temporarily)

1. Sometimes antivirus software blocks outgoing mail.
2. Temporarily disable email scanning in your antivirus.
3. Try sending the email again.
4. If it works, adjust your antivirus settings instead of keeping it disabled permanently.

Method 05: Send Smaller Attachments

If your email includes a large file:

1. Compress the file into a ZIP folder.
2. Or upload it to cloud storage and send the link instead.
3. Large attachments often trigger timeout errors.

Method 06: Create a New Outlook Profile

A damaged profile can cause sending issues.

1. Open Control Panel and click Mail → Show Profiles.
2. Click Add. Create a new profile and configure your account again.
3. Set the new profile as the default. Restart Outlook and test.

Professional Tool to Fix Outlook Error 0x8004210b

If your Outlook PST file is corrupted or damaged, you can use the DRS Outlook PST Recovery Tool. This tool helps repair damaged PST files and recover emails, contacts, attachments, and other mailbox data without data loss. It is useful when Outlook errors occur due to file corruption or oversized PST files. Preserves the original email formatting, structure, and metadata during the entire recovery. With its simple and user-friendly interface, every user can easily use it without needing any technical skills. 

Simple Steps to Fix Error 0x8004210b in Outlook

1. Download and install the DRS Outlook PST Recovery Tool.
2. Click on Open to add your corrupted or damaged PST files.
3. Choose Recovery Modes and other options. Click OK.
4. Then, you can preview all your recovered PST files.
5. Lastly, click Save and choose different Saving Formats.

Advanced Features of DRS Outlook PST Repair Tool

• Preview all your recovered Outlook PST files.
• Several Recovery Modes: “Standard”, “Advanced”, or “Deep”.
• A free version of this tool is available to evaluate its features.
• Moreover, this tool is highly compatible with all Windows & Mac versions.

Learn More: Top 10 Outlook Errors and How to Fix Them

Conclusion

In this blog, we explored the manual method and a professional tool to fix Outlook Error 0x8004210b. You can resolve the issue in many cases by using several manual methods. However, if the error continues even after trying all manual methods, the problem may be related to PST file corruption. In such situations, using a reliable tool can help repair the damaged file and recover mailbox data safely. So, download the free version of this tool to evaluate its features and functions.

Frequently Asked Questions