Download here the powershell script below for whitelistening.

In Powershell, execute following two commands to install these modules: 

Powershell: >> 
Install-Module -Name ExchangeOnlineManagement -Force 
Connect-ExchangeOnline 

After running the script on the tenant, verify:

Powershell: >>

Get-AntiPhishPolicy | Select Name, ExcludedDomains, ExcludedSenders

Then you can send a test phishing email from the platform under Phishing -> Phish Now to test directly.

Manual configuration (If step 3 on powershell fails)

If the script cannot execute Step 3 automatically, configure it manually as follows:

1. Navigate to security.microsoft.com
2. Go to: Email & Collaboration → Policies & Rules → Threat Policies
3. Click on Advanced Delivery
4. Select the Phishing Simulation tab
5. Add the following:

Configuration Details

6. Save the configuration.

In Powershell, execute following two commands to install these modules: 

Install-Module -Name ExchangeOnlineManagement -Force 

Connect-ExchangeOnline