outlook.com end to end encryption

Are your getting the error ‘An error occurred in the underlying security system. The supplied handle was invalid’ when trying to send an email in MS Outlook? Don’t worry, let us help you fix this problem.

Sending emails every day is almost an hobby for many Windows users. Moreover, users prefer sending emails by using email clients rather than webmail.

However, MS Outlook is popularly used by Windows 10 users. But, users complained of experiencing the ‘Outlook error in the underlying security system’ problem. This error problem prevents users from accessing Outlook data file and sending emails from Outlook.

How can I fix Outlook security system errors?

Solution 1: Restart your Internet Connection

Firstly, a quick fix you might want to try is to restart your internet connection. Sometimes, your ISP might be having issues, therefore, you might want to consider changing your ISP, as well.

However, to ascertain if your internet connection is really down, try to access a website in your browser. If you were unable to access it, then the issue is obviously due to a connection error. Restarting your internet connection might fix the problem.

Solution 2: Create a new Outlook profile

Firstly, you can easily fix this error by creating a new Outlook profile. In order to do that, follow these steps:

  • Press Windows Key + X to open Win+X menu and choose Control Panel from the list.outlook error in the underlying security system
  • In Control Panel click on Mail.
  • When Mail Setup window opens, click on Show Profiles button.
  • Click the Add button.
  • New Profile window will appear. Select E-mail Account option, enter your profile name and the required account information. Click Next.
  • Click Finish and your account will be created.

— READ ALSO: 5 best free and paid email backup software to use

By default, the above steps will create an IMAP account by default, if the email server supports it. However, you can also manually configure your email account, but beforehand you need to locate your Outlook data file. To do that, follow these steps:

  • Open Control Panel and click on Mail.
  • When Mail Setup window opens, click on Show Profiles button.
  • Select your current Outlook profile and click on Properties.
  • Click on Data Files button.
  • Account Settings window will now appear. Go to Data Files tab. You should see the name and the location of the data file. Remember the location of the data file because you’ll need it for later steps.

Also, you can configure your email account manually, do the following:

  • Go to Control Panel and select Mail.
  • Click on Show Profiles and click the Add button.show outlook mail profile
  • Enter the profile name and click OK.</li>
  • In Add New Account window select ‘Manually configure server settings’ or additional server types and click ‘Next’.
  • In Choose service dialog box select Internet E-mail and click Next.
  • Enter your account details in Internet E-mail Settings window.
  • In Deliver new messages to section select Existing Outlook Data File, click Browse and locate your data file.
  • Click ‘Next’ and your new Outlook profile should be successfully created.

Alternatively, you can back up your data file and delete your Outlook profile before creating a new one and linking it to the data file. Creating a new profile will remove all your settings, but it should fix the Outlook error in the underlying security system problem.

Solution 3: Set the Inbox folder

Outlook error in the underlying security system can occur if the Inbox folder isn’t specified. To fix this problem follow these steps:

  • Go to File &gt; Account Settings > Account Settings.
  • Click the Change Folder and click the + next to the folder name to expand it.
  • Click Inbox and click OK.
  • Close Account Settings and click Send and Receive button.

Alternatively, you can create a different folder; this folder can be used to store your emails. If the outlook error in the underlying security syst>em prompt still persists, proceed to the next solution.

Solution 4: End all Outlook related processes

Sometimes, software conflicts might occur, due to several Outlook processes that runs in the background resulting the in Outlook error in the underlying security system.

In order to easily end MS Outlook related processes, follow these steps:

  • Go to Start > Type “Task Manager”, and then hit the Enter button.Thunderbird won't start Windows 7
  • Now, locate Outlook-related processes(any processes that have Lync, Communicator, ucmapi or Outlook) and click on it.
  • Then, click on “End Process” option.
  • Restart Outlook afterwards, and check if the problem is resolved.

However, if you still encounter Outlook…. error in the underlying security system problem, proceed to the next solution.

Solution 5: Switch Off Anti-virus Software

Outlook error in the underlying security system can be caused by antivirus software. Some antivirus tools can impede Outlook’s incoming and outgoing emails.

Antivirus software can be disabled by right-clicking their system tray icons and selecting a disable, pause or exit option. Alternatively, you can also temporarily disable antivirus protection from Task manager, here’s how to do this:

  • Right-click the Windows 10 taskbar and select Task Manager.Thunderbird won't start Windows 7
  • Select the Task Manager’s Start-up tab shown in the shot below.
  • Now, select your antivirus utility, and press the Disable button.

Solution 6: Switch Off the Windows Firewall

Windows Firewall is can also block MS Outlook thereby causing Outlook error in the underlying security system. So, you may have to switch off the firewall off.

Follow these steps to configure the Windows Firewall settings in Windows 10.

  • Click the Cortana button on the taskbar to open that app.
  • Input the keyword ‘Windows Firewall’ in Cortana’s search box, and then select to open Windows Defender Firewall.
  • Click Turn Windows Firewall on or off to open the options shown directly below.outlook error in the underlying security system
  • Select both the Turn off Windows Defender Firewall options there, and then press the OK button.outlook error in the underlying security system
  • Alternatively, you can check if Outlook is permitted through the Windows Firewall by clicking Allow an app or feature through Windows Defender Firewall.outlook error in the underlying security system
  • Press the Change settings button, and then scroll to Outlook in the Allowed apps list.
  • Select both Outlook’s check boxes if they are not ticked.
  • Then press the OK button to confirm the new setting.

Solution 7: Run Outlook in Safe Mode

Just like other applications, MS Outlook has a Safe Mode; this can be used to resolve Outlook error in the underlying security system dilemma as well. The Safe Mode launches Outlook without any add-ins to ensure that there are no software conflicts.

Follow these steps to open Outlook in Safe Mode:

  • Open the Win + X menu by pressing the Win key + X hotkey.
  • Then click Run on the Win + X menu to open its window.
  • Enter ‘Outlook /safe’ in Run’s text box, and press the OK button.
  • A Choose Profiles window will then open. Press the OK button on that window.

— READ ALSO: 5 of the best email privacy software for 2018

Solution 8: Increase the Server Timeouts Setting in Outlook

In addition, MS Outlook comprises a ‘Server Timeouts’ menu that can fix interrupted connections issues. Therefore, this option is worth mention for fixing the Outlook error in the underlying security system problem.

Here’s how to increase the Server Timeouts setting in Outlook 2010.

  • First, open the Outlook software; and then select the File tab.
  • Press the Account Settings button and click Account Settings to open the E-mail Accounts window.
  • Then press the Change > More Settings buttons to open the E-Mail Settings window.
  • Click the Advanced tab, and then can drag the Sever Timeouts bar to the far right.
  • Press the OK button to close the window.

Those are applicable resolutions that might fix the Outlook error in the underlying security system so that you can send emails with MS Outlook again.

If you do have any question concerning Outlook error in the underlying security system problem, let us know by commenting below.