Outlook error 421 is one of the most common error which you can encounter while using Outlook email client. Despite being a popular personal information manager, it is not free from the occasional flaws. As a result of which you can encounter this type of errors with your device. If you have already faced this issue and want to resolve it, then you can follow this article to the end. It consists of several guidance following which you can easily resolve the matter on a quick note. But before going on that part, at first, let’s focus on the causes as well as the symptoms for which you can encounter this error in your device.

Symptoms for Outlook Error 421:

Once you encounter Outlook error 421 in your device, your device will crash all of a sudden. Moreover, you will also receive an error message showing the server responded: 421 cannot connect to the SMT / SMTP server”. Now, let’s know the causes which led to this issue.in your Outlook mail.

Know Why Outlook Error 421 Cannot Connect To SMT?

Due to several reasons, you can encounter this Outlook error 421 in your device. For instance-

  • Outlook Configuration Error –  In most of the cases, you can encounter this particular error due to some configuration mistake present in the system.
  • Firewall Related Issues – You can also encounter this error due to some inconvenience present in your Windows Firewall. However, in some cases, due to a third party antivirus software, the users get this error
  • Port 25 Traffic Error – The user also comes across this error due to blocked traffic on port 25.  
  • VPN connection- Sometimes, due to VPN error, this error occurs in your device. Because most of the VPN ’s does not contain the email server present in your wishlist.

Now, as you have become aware of the causes due to which you are getting this error. Further, you should focus on the solutions to resolve this particular error.

Easy Hacks To Fix Outlook Error 421 With Ease:

In order to resolve the Outlook error 421, you have to follow the steps mentioned below.

Method 1: Resolve Configuration Problems

If Outlook error 421 cannot connect to smt occurs due to configuration problems, then you can fix it by going through some simple procedure mentioned below:

  1. At first, open the Outlook and go to the File option.
  2. After that, click on the Account Settings.
  3. Once done, choose the account which you want to use and tap on the Remove button.
  4. After that, you will be able to remove the account. Tap on the option named New button.
  5. Once done, tap on the Email account and insert all of the credentials again.
  6. Tap on the option named Next.

Once done, try to check whether you successfully able to resolve the matter or not.

If you won’t able to perform this action, then you can follow the next method mentioned below.

Method 2: Change SMTP Port Number

You can also encounter this error because of the SMTP port filtered by the ISP. In that case, try to do the following:

  1. At first, go to the File and click on the Account settings.
  2. Once done, try to select the account due to which you are getting this error. Once done, tap on the Change button.
  3. In this wizard, you have to go to the More settings at the Advanced tab.
  4. Once done, type the 465 in the box near the Outgoing server (SMTP). Be sure that the type of encryption is SSL.

Now, check the status of the error. If this error persists, then try to follow the next method mentioned below.

Method 3: Check the Firewall

It can also happen that you are getting this error due to some inconvenience present in the firewall. Else, a third-party firewall mistakenly or maliciously blocked some IP address. As a result of which you are encountering this error in your PC. If this is the case, then try to disable the firewall due to which you are getting this error.

Method 4: Check the VPN Interface

In case, if you encounter this kind of errors in your device due to a problem in a VPN connection, then you can check for the VPN interface to resolve this particular error. In this case, there are chances that the VPN fails to connect with the mail server. As a result of which, you can encounter this kind of errors with your device.

After performing these steps, you will be able to resolve the matter on your own.

Final Words

Hopefully, using these hacks and tricks, you will be able to resolve the Outlook error 421 on your own. But for that, you have to follow each and every step carefully, which are recommended, not to jump any one of them. Otherwise, you won’t be able to resolve the matter on your own. If you encounter any kind of glitches while performing the hacks and tricks, then you can leave a comment in the comment section. Hope that you have found this article helpful enough.

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