Office 365: List of Groups and Owners

For Microsoft 365 Groups:

# 1. Connect (ensure you have the right scopes)
Connect-MgGraph -Scopes "Group.Read.All", "User.Read.All"

# 2. Build the User Cache (The "Secret Sauce" for speed)
# We fetch ID, Name, and Email once and store them in a Hashtable (Key = ID)
Write-Host "Building user cache..." -ForegroundColor Cyan
$UserCache = @{}
Get-MgUser -All -Property Id, DisplayName, Mail | ForEach-Object {
$UserCache[$_.Id] = $_
}

# 3. Retrieve all groups
Write-Host "Fetching groups and mapping owners..." -ForegroundColor Cyan
$AllGroups = Get-MgGroup -All -Property Id, DisplayName, GroupTypes

$GroupReport = foreach ($Group in $AllGroups) {
Write-Host "Starting group: $Group" -ForegroundColor Cyan

# Get just the IDs of the owners for this group
$OwnerLinks = Get-MgGroupOwner -GroupId $Group.Id

if ($OwnerLinks) {
foreach ($Link in $OwnerLinks) {
# Lookup the owner in our local cache instead of calling the API
$Owner = $UserCache[$Link.Id]

[PSCustomObject]@{
GroupName = $Group.DisplayName
GroupType = ($Group.GroupTypes -join ", ") -replace "Unified", "M365 Group"
OwnerName = if ($Owner) { $Owner.DisplayName } else { "Unknown (Service Principal or Deleted)" }
OwnerEmail = if ($Owner) { $Owner.Mail } else { "N/A" }
OwnerId = $Link.Id
}
}
} else {
# Optional: Include groups that have no owners
[PSCustomObject]@{
GroupName = $Group.DisplayName
GroupType = ($Group.GroupTypes -join ", ")
OwnerName = "--- NO OWNER ---"
OwnerEmail = "N/A"
OwnerId = "N/A"
}
}
}

# 4. Output the results
$GroupReport | Out-GridView

For Distribution Lists:

Connect-ExchangeOnline

# 2. Setup a local cache to resolve GUIDs to Names efficiently
$RecipientCache = @{}

Write-Host "Fetching Distribution Lists..." -ForegroundColor Cyan
$AllDLs = Get-DistributionGroup -ResultSize Unlimited | Where-Object { $_.RecipientTypeDetails -eq "MailUniversalDistributionGroup" }

$DLReport = foreach ($DL in $AllDLs) {
    Write-Host "Processing: $($DL.DisplayName)" -ForegroundColor Gray

    # Resolve each manager in the list
    $ResolvedManagers = foreach ($ManagerIdentity in $DL.ManagedBy) {
        
        # If we've already looked up this GUID/Identity, use the cached name
        if ($RecipientCache.ContainsKey($ManagerIdentity)) {
            $RecipientCache[$ManagerIdentity]
        } 
        else {
            # Look up the name from Exchange
            $Found = Get-Recipient -Identity $ManagerIdentity -ErrorAction SilentlyContinue
            $Name = if ($Found) { $Found.DisplayName } else { $ManagerIdentity }
            
            # Save to cache for the next time we see this person
            $RecipientCache[$ManagerIdentity] = $Name
            $Name
        }
    }

    [PSCustomObject]@{
        DisplayName   = $DL.DisplayName
        PrimaryEmail  = $DL.PrimarySmtpAddress
        Managers      = $ResolvedManagers -join "; "
        Alias         = $DL.Alias
    }
}

# 3. Output
$DLReport | Out-GridView

(Get-DistributionGroup -Identity "**NAME_OR_ADDRESS**").ManagedBy

$AllDLs = Get-DistributionGroup -ResultSize Unlimited | Where-Object { $_.RecipientTypeDetails -eq "MailUniversalDistributionGroup" }
$DLstoChange = $AllDLs | Where-Object {$_.managedby -eq "**OLD_OWNER_FROM_ABOVE**"}
$DLstoChange | Set-DistributionGroup -ManagedBy "**NEW_OWNER**"