# ==========================================
# Change Outlook to Online Mode for All Users
# ==========================================
param(
    [string[]]$ExcludedUsers
)
$OfficeVersions = @("16.0","15.0","14.0")
# Get all user SIDs except system accounts
$ExcludedSIDs = @(
    "S-1-5-18",  # SYSTEM
    "S-1-5-19",  # LOCAL SERVICE
    "S-1-5-20"  # NETWORK SERVICE
    #"S-1-5-80-*" # All service accounts (NT SERVICE\*)
)
foreach ($user in $ExcludedUsers) {
    try {
        $sid = (New-Object System.Security.Principal.NTAccount($user)).
               Translate([System.Security.Principal.SecurityIdentifier]).
               Value
        Write-Host "[INFO] Excluding User: $user"
        Write-Host "[INFO] SID: $sid"
        $ExcludedSIDs += $sid
    }
    catch {
        Write-Host "[WARNING] Failed to get SID for user: $user"
    }
}
$subKeys = Get-ChildItem "Registry::HKEY_USERS" |
    Where-Object {
        $_.Name -notmatch "_Classes$" -and
        $_.PSChildName -notin $ExcludedSIDs -and
        $_.PSChildName -notmatch "^S-1-5-80-"
    }
# Close Outlook
Write-Host "Closing Outlook..."
Get-Process OUTLOOK -ErrorAction SilentlyContinue | ForEach-Object {
    $_.CloseMainWindow() | Out-Null
    if (!$_.WaitForExit(10000)) {
        Write-Host "Force closing Outlook..."
        $_ | Stop-Process -Force
    }
}
Start-Sleep -Seconds 2
foreach ($sid in $subKeys) {
    Write-Host ""
    Write-Host "Processing SID: $($sid.PSChildName)"
    $RegPath = $null
    foreach ($version in $OfficeVersions) {
        $BasePath = "Registry::HKEY_USERS\$($sid.PSChildName)\Software\Microsoft\Office\$version\Outlook\Profiles"
        if (Test-Path $BasePath) {
            Write-Host "Detected Outlook Version: $version"
            $RegPath = Get-ChildItem -Path $BasePath -Recurse |
                Where-Object {
                    try {
                        (Get-ItemProperty $_.PSPath -ErrorAction Stop)."00036601" -ne $null
                    }
                    catch {
                        $false
                    }
                } |
                Select-Object -First 1 -ExpandProperty PSPath
            if ($RegPath) {
                break
            }
        }
    }
    if (-not $RegPath) {
        Write-Host "No Outlook profile found for SID: $($sid.PSChildName)"
        continue
    }
    Write-Host "Detected Registry Path:"
    Write-Host $RegPath
    Write-Host "Changing Outlook to Online Mode..."
    try {
        $currentValue = (Get-ItemProperty -Path $RegPath -ErrorAction SilentlyContinue)."00036601"
        # 0x04 = Cached Exchange Mode enabled
        if ($currentValue -and ($currentValue[0] -eq 4)) {
        # Set Online Mode
        Set-ItemProperty `
            -Path $RegPath `
            -Name "00036601" `
            -Value ([byte[]](0,0,0,0)) `
            -Type Binary
        Write-Host "[SUCCESS] Registry updated for SID: $($sid.PSChildName)"
            } else {
    Write-Host "[INFO] Already in Online Mode or unknown state. Skipping."
}    
    }
    catch {
        Write-Host "[ERROR] Failed to update registry for SID: $($sid.PSChildName)"
        Write-Host $_.Exception.Message
    }
    # Verify value
    $value = (Get-ItemProperty -Path $RegPath)."00036601"
    Write-Host "Current Registry Value:" ($value -join " ")
}
Start-Sleep -Seconds 2
# Restart Outlook
Write-Host "`n[INFO] Restarting Outlook..."
try {
    Start-Process "outlook.exe"
    Write-Host "[SUCCESS] Outlook restarted."
}
catch {
    Write-Host "[WARNING] Could not automatically start Outlook."
    Write-Host $_.Exception.Message
}
Write-Host "Done."