#Test ( Whatif ) 
Get-ADUser -Filter {UserPrincipalName -like "*@domain.com"} -property msExchHideFromAddressLists | Set-ADObject -Replace @{msExchHideFromAddressLists=$true} -Whatif

#Production Change
Get-ADUser -Filter {UserPrincipalName -like "*@domain.com"} -property msExchHideFromAddressLists | Set-ADObject -Replace @{msExchHideFromAddressLists=$true}