When rolling out classifications on Teams in an existing environment it can be good to know how many Teams that already have Guest Users invited. To gather this information I put together an easy PowerShell script. Running this script requires that you install the Microsoft Teams PowerShell module.

#Array for Teams with Guests
$teamswithguests = @()
#Collect all Teams in tenant
$teams = get-team
#Loop to get all Teams with Guests accounts
foreach ($team in $teams){
  #Get groupid 
  $groupid = $team.groupid
  #search through teams with guest users
  $users = Get-TeamUser -GroupId $groupid |where role -eq "Guest"
  $count = $users.count
    if ($count -eq "0"){
        Write-host "there are no external user added $($team.DisplayName)" -ForegroundColor Cyan
        $teamswithguests += $team
        Write-Host "Team $($team.DisplayName) has these external members" -ForegroundColor DarkMagenta
#List teams with Guest users

Hope this will help you in your Teams rollout.

Regards @jlindoe