Microsoft Outlook is one of the best and most popular email applications that Windows users often use to send and receive emails to workstations. Mostly, Outlook is used in professional offices for faster communication. 421 cannot connect to SMTP server is one of the annoying error users get on the system. This error appears when the SMTP / SMT server settings are wrong. If you are Windows users and facing the Outlook error 421 then you can try the undermentioned methods to fix this particular issue on the system.
Causes of 421 Cannot Connect To SMTP Server
There are various causes that trigger the error: ‘421 cannot connect to SMPT server’ in Outlook on your PC. We have listed some of them below.
- A problem with the Outlook settings can cause the Outlook error 421 cannot connect to SMTP server. This problem occurs with a reconfigured email account.
- Some third-party anti-viruses and Windows firewall are configured to block connections to different IP areas where the Outlook mail server is established. This is probably the main reason to display the Outlook error 421.
- Another cause is that to minimize the automatic spam, some of the ISPs block the traffic above port 25. Although this helps prevent infected computers from the Spam network, this can sometimes show the 421 error on Outlook.
- Sometimes, this issue occurs if the Outlook installation file is corrupted.
- If you are using the older version of the Windows Operating system, then this can also cause the Outlook error 421 cannot connect to SMT.
These are the causes behind the occurrence of the error message. Users must utilize proper solutions to fix Outlook error 421 on the system.
Best Methods to Resolve the 421 Cannot Connect to the SMTP Server Issue
At first, you have to restart the system. After restarting the system, if the issue is still present, then you need to follow other methods. Below we are going to list some of the most useful methods that will help you to fix the 421 cannot connect to the SMT / SMTP server problem and send messages in Outlook regularly.
Method 1 – Fixing the Outlook Configuration Issues
If you newly configured the Outlook account, then it’s possible that the Outlook error 421 is generated by a configuration error. If you type a wrong mail server name or the port setting are wrong, then you can see the ‘421 cannot connect to SMTP server’ error while accepting or forwarding an email. So, you need to remove it and again add your Outlook account. To do so follow the steps mentioned below:
At first, you have to launch the Outlook account to put the ID and Password. In the Outlook window, take the mouse to the File tab, and click on it to launch the drop-down menu list.
From the drop-down menu list, you need to select the Account Settings. In that section, you need to select the account. Then, you should see the Remove button which is located on the right side. Click on it. Now the account is eliminated from your computer.
Once it is deleted, you should click on the New option. In the next window, you must select the Email account and put the important information properly. After that, click on the Next button. Then, wait for a few seconds to configure the email and then send a test email. If the test mail is addressed then your Outlook account is configured. If not, then you need to follow to the next method.
Method 2 – Modifying the SMTP Port Number
Sometimes, you can face this issue when you put the wrong SMTP port number. So, you must modify it. To do so, follow the under mentioned steps:
First, go to your Outlook account. When it opens, move the cursor to the File section, and select it. Then click on the Account Settings option under the File menu list.
From the Account Settings window, you must select your account and then click on the Change button.
In the Change Account window, you have to navigate to ‘More Settings’ which is located at the below right corner.
In the Internet Email Settings, you must click on the Advanced tab and then modify the Outgoing server(SMTP), set to 465 and then set the encrypted connection to SSL.
Method 3 – Remove the Third-Party Antivirus Software
This is one of another method that can help you to resolve the 421 cannot connect to SMTP server issue on the system. Follow the steps given below:
Firstly, you must open the Control Panel by typing in the Search box and then hit the Enter key. Alternately, hold the Windows logo button and at the same time press the X key to launch the Menu list. Select Control Panel.
When the Control Panel application opens, double click on the Programs and Features section to open it. In that window, you will find the Third-party antivirus. Select it and click on the Uninstall option.
Once the uninstallation process is complete, restart your PC and then check whether the issue is eliminated or not.
Method 4 – Remove Outlook and Reinstall
After performing the methods as mentioned above, if the issue still persists, then you need to use this method to resolve the 421 cannot connect to SMTP server issue on the system. In order to resolve this issue, follow the points cited below.
Press the Win + R buttons together to launch the Run dialog window. Type Control Panel and then press the Enter button or click on the OK option. Alternatively, press the Start button from the keyboard to open the list. Then, choose Control Panel.
You have to select the Programs and Features tab from the Control Panel. In the Programs and Features tab, scroll down the programs page and locate the Third-Party antivirus, and right click on it to launch the drop-down list. Choose the Uninstall button to remove it completely.
Once Outlook is removed, restart the system. After restarting the system, download Outlook again from the Outlook official website. Once the download is finished, install it. Follow the onscreen directions carefully to complete the installation process. Once it is installed, open the Outlook account and try to send the mail.
Method 5 – Update the Operating System
By updating the Operating System also, you can fix the 421 cannot connect to SMTP server issue on your PC. To update the system, follow the steps given below.
In the beginning, you need to type the Settings in the Search panel and then hit the Enter button. Alternately, you can also open the Settings application by pressing the Windows button + I key together.
In the next window, you can see the Settings application and locate the Update and Security section. On the left side menu list, you can see the Update tab. Click on it.
In that tab, you will find your PC version. Below you can see an option Check for updates. Click on it. Now, the system will check whether any updates are available or not. If there are, then you need to select the Update button. Once it finishes, reboot the system and then check if your Outlook account works perfectly without any issue.
Hopefully, now you understand the fixes for 421 cannot connect to SMTP server issue on your PC. After performing all the methods, if the issue still persists, then you need to talk to the experts.