Get-ADGroupmember

Try the following (ensure you have the Active Directory module for PowerShell installed)

# Define the path to save the CSV file
$outputFile = "C:\ExportedUsers.csv"

# Get all groups by filtering for security groups, mail-enabled security groups, and distribution groups
$groups = Get-ADGroup -Filter {GroupCategory -eq 'Security' -or GroupCategory -eq 'Distribution'}

# Initialize an empty array to store results
$results = @()

# Iterate over each group
foreach ($group in $groups) {
    # Get all members of the group, including those in nested groups
    $members = Get-ADGroupMember -Identity $group -Recursive | Where-Object { $_.objectClass -eq 'user' }
    
    # Add each member's details to the results array
    foreach ($member in $members) {
        $results += [pscustomobject]@{
            GroupName = $group.Name
            UserName = $member.SamAccountName
            UserDisplayName = $member.Name
            UserEmail = $member.EmailAddress
        }
    }
}

# Export results to a CSV file
$results | Export-Csv -Path $outputFile -NoTypeInformation -Encoding UTF8

Write-Output "Export completed: $outputFile"

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hth

Marcin