Get the email addresses of group members using a CN path and ldap query.

Get-EmailsOfGroupMembersRecursively.ps1

$SaveLocation = "$home\Desktop\emails.csv"
Write-Output 'Querying for email addresses of all group members. This may take a few minutes...'

$Searcher = New-Object DirectoryServices.DirectorySearcher
$Filter = '(&(objectCategory=person)(ObjectClass=user)(|(memberOf:1.2.840.113556.1.4.1941:=CN=AllFaculty,OU=Staff Faculty,DC=domain,DC=local)(memberOf:1.2.840.113556.1.4.1941:=CN=Allstaff,OU=Staff Faculty,DC=domain,DC=local)(memberOf:1.2.840.113556.1.4.1941:=CN=AllAdjunct,OU=Staff Faculty,DC=domain,DC=local))(!(userAccountControl:1.2.840.113556.1.4.803:=2)))'
$Searcher.Filter = $Filter
$Searcher.SearchRoot = 'LDAP://DC=domain,DC=local'

$Users = $Searcher.FindAll()

$Emails = @()
foreach ($Result in $Users) {
    if ($Result.Properties.mail -ne $null -and $Result.Properties.mail -ne '') {
        $Obj = New-Object PSObject
        $Obj | Add-Member -MemberType NoteProperty -Name email -Value ([string]$Result.Properties.mail.Trim())
        $Emails += $Obj
    }
}

if ($Emails.count -gt 0) {
    Write-Output "Found $($Emails.count) emails. Saving them to $SaveLocation"
    $Emails | Export-Csv $SaveLocation -NoTypeInformation
} else {
    Write-Output "Found 0 emails. An error probably occurred."
}

Write-Host -NoNewLine 'Press any key to continue...'
$null = $Host.UI.RawUI.ReadKey('NoEcho,IncludeKeyDown')