PowerShell: Microsoft Exchange to Require that all Senders are Authenticated

In this scenario, the business decision is to limit exposure of certain internal accounts to only allow those to receive emails from the same “Exchange Organization”. This is an extra measure to improve enterprise security posture by further reducing spams and potential messaging vulnerabilities.

# Set "Require that all senders are authenticated" for one account
$targetUsername="PORequests"
$targetObject = Get-ADUser -Filter 'SamAccountName -eq $targetUsername'
Set-ADUser $targetObject -Replace @{msExchRequireAuthToSendTo = $True}

# Set "Require that all senders are authenticated" for all Distribution Groups
$distributionGroups = Get-ADGroup -Filter 'groupcategory -eq "distribution"'
ForEach ($group In $distributionGroups){
	#$group.Name
	Set-ADGroup $group -Replace @{msExchRequireAuthToSendTo = $True}
}