I have a number of test accounts which were assigned O365 licenses and subsequently appeared in the GAL. I didn’t want them cluttering up the GAL but didnt want to go through each account manually.

Import the ActiveDirectory PS module:

Import-Module activedirectory

To find the status of an account’s msExchHideFromAddressLists, you can use:

Get-ADUser -Identity "ado-01-test" -property msExchHideFromAddressLists

but if the account has not had a value set, nothing will be returned for “msExchHideFromAddressLists”.

If you have a number of accounts to amend, you can pattern match for account attributes:

Get-ADUser -Filter ("DisplayName -like '*-test*'") | `  
Select Name, SamAccountName, UserPrincipalName | `  
Export-csv C:\Users\andy\Desktop\userlist.csv -NoTypeInformation

This will create a list of all users who have “-test” in their display name and export it to a csv file which you can manually check.

To import the checked csv:

$users = Import-csv -Path C:\Users\andy\Desktop\userlist.csv

To set multiple accounts’ msExchHideFromAddressLists to true:

foreach ($user in $users){
Get-ADuser -Identity $user.SamAccountName -property msExchHideFromAddressLists   
Set-ADObject -Replace @{msExchHideFromAddressLists=$true}
}

To check the amended values, run:

foreach ($user in $users){
	Get-ADuser -Identity $user.SamAccountName -property msExchHideFromAddressLists
}

and you will see something like:

DistinguishedName : CN=ado-01-test,OU=Testing,DC=MyDomain,DC=Test
Enabled : True
msExchHideFromAddressLists : True
Name : ado-01-test
ObjectClass : user
SamAccountName : ado-01-test
UserPrincipalName : ado-01-test@mydomain.test