How to fix error 0x8004210A in Microsoft Outlook

Error 0x8004210A is a timeout error typically associated with email clients like Microsoft Outlook when they are unable to receive or send emails within the expected time frame. This is commonly caused by issues such as slow internet connections, incorrect server settings, or large email attachments. Here’s how to fix it:

1. Check Internet Connection

• Ensure your internet connection is stable. If it’s slow or unstable, try restarting your router or switching to a different network.

2. Review Email Account Settings

• IMAP/POP3 settings: Ensure your incoming (IMAP or POP3) and outgoing (SMTP) server settings are correct. You can typically get these from your email provider.
• Double-check that your ports are configured correctly:
  • POP3: Port 110 (non-encrypted) or 995 (SSL)
  • IMAP: Port 143 (non-encrypted) or 993 (SSL)
  • SMTP: Port 25 (non-encrypted) or 465/587 (SSL/TLS)

3. Increase Server Timeouts

• In Outlook, go to:
  • File > Account Settings > Change Account
  • Under the server settings, click More Settings ? Advanced tab.
  • Increase the server timeout slider to a higher value (e.g., 5 minutes).

4. Disable or Adjust Security Software

• Temporarily disable any antivirus or firewall software to check if it’s interfering with Outlook’s connection.
• Ensure that your antivirus is not scanning outgoing or incoming emails, which can delay the connection.

5. Repair Outlook Data File

• If the issue persists, your Outlook data file might be corrupted. Use the Inbox Repair Tool (scanpst.exe) to repair the .pst or .ost file:
  1. Locate scanpst.exe on your computer (typically in your Office installation folder).
  2. Run the tool, browse for your Outlook data file, and follow the steps to repair it.

6. Update or Reinstall Outlook

• Ensure you are using the latest version of Outlook. Updates often fix bugs that could cause timeout errors.
• If updating doesn’t help, consider reinstalling Outlook to eliminate any corrupted files or settings.

7. Check Email Size or Connection Speed

• Large emails with attachments can sometimes trigger the timeout. Try removing large outgoing emails from the Outbox and receiving smaller emails first.

These steps should help resolve error 0x8004210A in most cases.