SMTP Error 421

SMTP Error 421

While sending an email on Microsoft Outlook, if the ‘server responded: 421 cannot connect to SMTP server’ error message appears, refer to the instructions mentioned below to clear it. The main reason for the SMTP error 421 problem is due to incorrect SMTP server settings.

Scenario 1 :

If the error 421 problem occurs once you configure the email account on the Microsoft Outlook application, remove the existing account, and reconfigure it using the automatic configuration method.

  • Step 1: At first, launch the main window of the Outlook application, click the File tab and choose the Account Settings option.
  • Step 2: Now, the Account Settings dialog window will be displayed on the screen.
  • Step 3: Choose your existing email address and click the Remove button at the top.
  • Step 4: This will remove the email account from the Microsoft Outlook application.
  • Step 5: Once done, click the New button and select the radio button next to the Email Account option.
  • Step 6: Once you provide the correct details in the Your Name, Email Address, Password, and Retype Password fields, click the Next button.
  • Step 7: If the email configuration is done successfully, the Congratulations message will appear on the screen.
  • Step 8: Click the Finish button and check if the SMTP error 421 problem has been resolved.

Scenario 2 :

If you were able to send emails previously without the error 421 problem, but if you see this error now, refer to the steps mentioned here.

  • Step 1: After you open the Microsoft Outlook application, click File -> Account Settings.
  • Step 2: Select your email account and click the Change button in the Account Settings window.
  • Step 3: As soon as the Change Account window opens, click the More Settings button.
  • Step 4: Navigate to the Advanced tab, enter 465 in the Outgoing Server (SMTP) field, and choose the SSL option from the ‘Use the following type of encrypted connection’ drop-down menu.
  • Step 5: Close the OK button and check if the SMTP error problem has been resolved.
  • Step 6: If the problem persists, check if some third-party firewall program is interfering with Outlook.
  • Step 7: If you use a VPN, it might also prevent the Outlook application from communicating with the email server.
  • Step 8: Disable the VPN connection and turn off your antivirus program temporarily. Try to send emails through Microsoft Outlook.
  • Step 9: If you are still facing SMTP error 421 issues, you can contact us for remote assistance.

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