# Event ID 15004 - Medium Pressure
Log Name:      Application
Source:        MSExchangeTransport
Event ID:      15004
Level:         Warning
Description:   Resource pressure is Medium. UsedDiskSpace = 89%

# Event ID 15005 - High Pressure
Log Name:      Application
Source:        MSExchangeTransport
Event ID:      15005
Level:         Error
Description:   Resource pressure is High. UsedDiskSpace = 96%
               Inbound mail submission has been paused.

# View transport resource utilization
Get-ExchangeDiagnosticInfo -Process EdgeTransport -Component ResourceThrottling |
    Select-Object -ExpandProperty ComponentStates

# Alternative: Check transport agent status
Get-TransportPipeline | Format-List

# Get detailed resource utilization
[xml]$bp = Get-ExchangeDiagnosticInfo -Process EdgeTransport -Component ResourceThrottling
$bp.Diagnostics.Components.ResourceThrottling.ResourceTracker.ResourceMeter |
    Select-Object Resource, Pressure, CurrentResourceUse, PreviousResourceUse |
    Format-Table -AutoSize

# Check disk space on queue database drive
Get-WmiObject Win32_LogicalDisk |
    Select-Object DeviceID, @{N='FreeGB';E={[math]::Round($_.FreeSpace/1GB,2)}},
    @{N='TotalGB';E={[math]::Round($_.Size/1GB,2)}} | Format-Table

# View all queues and message counts
Get-Queue | Select-Object Identity, DeliveryType, Status, MessageCount, NextHopDomain |
    Sort-Object MessageCount -Descending | Format-Table -AutoSize

# Check for poison messages
Get-Queue -Identity "Poison" | Format-List

# Get back pressure events from last 24 hours
Get-WinEvent -FilterHashtable @{
    LogName = 'Application'
    ProviderName = 'MSExchangeTransport'
    Id = 15004,15005,15006,15007
    StartTime = (Get-Date).AddHours(-24)
} | Select-Object TimeCreated, Id, Message | Format-Table -Wrap

# 1. Find and clean transport queue folder
$queuePath = (Get-TransportService).QueueDatabasePath
Write-Host "Queue database location: $queuePath"

# 2. Clear old temp files (safe to delete)
Get-ChildItem "$queuePath\..\temp" -Recurse |
    Where-Object { $_.LastWriteTime -lt (Get-Date).AddDays(-1) } |
    Remove-Item -Force

# 3. Clear IIS log files if on same drive
Get-ChildItem "C:\inetpub\logs\LogFiles" -Recurse -Include *.log |
    Where-Object { $_.LastWriteTime -lt (Get-Date).AddDays(-7) } |
    Remove-Item -Force

# 4. Restart transport service to reset pressure
Restart-Service MSExchangeTransport

# 5. Verify back pressure cleared
Start-Sleep -Seconds 30
Get-EventLog -LogName Application -Source MSExchangeTransport -Newest 5 |
    Where-Object { $_.EventID -in 15004,15005,15006 } | Format-Table TimeGenerated, EventID, Message -Wrap

# Check what's consuming space
$queueDrive = (Get-TransportService).QueueDatabasePath.Substring(0,2)
Write-Host "Analyzing drive $queueDrive..."

# Find large files in Exchange paths
$exchangePaths = @(
    "$queueDrive\Program Files\Microsoft\Exchange Server\V15\TransportRoles",
    "$queueDrive\Program Files\Microsoft\Exchange Server\V15\Logging"
)

foreach ($path in $exchangePaths) {
    if (Test-Path $path) {
        Get-ChildItem $path -Recurse -File |
            Sort-Object Length -Descending |
            Select-Object -First 20 FullName, @{N='SizeMB';E={[math]::Round($_.Length/1MB,2)}} |
            Format-Table -AutoSize
    }
}

# Safe cleanup of protocol logs older than 30 days
$logPaths = Get-ChildItem "$queueDrive\Program Files\Microsoft\Exchange Server\V15\Logging" -Directory
foreach ($logPath in $logPaths) {
    $oldLogs = Get-ChildItem $logPath.FullName -Recurse -File |
        Where-Object { $_.LastWriteTime -lt (Get-Date).AddDays(-30) }
    if ($oldLogs) {
        Write-Host "Removing $($oldLogs.Count) old logs from $($logPath.Name)..."$logPath.Name)..."
        $oldLogs | Remove-Item -Force
    }
}

# Configure circular logging for protocol logs (prevents growth)
Set-TransportService -Identity $env:COMPUTERNAME -ReceiveProtocolLogMaxAge 7.00:00:00
Set-TransportService -Identity $env:COMPUTERNAME -SendProtocolLogMaxAge 7.00:00:00

# Check EdgeTransport memory usage
$edgeProcess = Get-Process EdgeTransport -ErrorAction SilentlyContinue
if ($edgeProcess) {
    Write-Host "EdgeTransport Memory: $([math]::Round($edgeProcess.WorkingSet64/1GB,2)) GB"2)) GB"
    Write-Host "EdgeTransport Private Memory: $([math]::Round($edgeProcess.PrivateMemorySize64/1GB,2)) GB"2)) GB"
}

# Check system memory
$os = Get-WmiObject Win32_OperatingSystem
$freeMemGB = [math]::Round($os.FreePhysicalMemory/1MB,2)
$totalMemGB = [math]::Round($os.TotalVisibleMemorySize/1MB,2)
Write-Host "System Memory: $freeMemGB GB free of $totalMemGB GB total"$totalMemGB GB total"

# If memory is low, restart transport to release memory
if ($freeMemGB -lt 2) {
    Write-Host "Low memory detected. Restarting transport service..."
    Restart-Service MSExchangeTransport -Force
}

# Reduce memory footprint by adjusting thresholds
# Note: Requires EdgeTransport.exe.config edit and service restart
Write-Host "Consider adjusting memory thresholds in EdgeTransport.exe.config if recurring"

# Check queue database size
$queuePath = (Get-TransportService).QueueDatabasePath
$queueDb = Get-ChildItem "$queuePath\mail.que" -ErrorAction SilentlyContinue
if ($queueDb) {
    Write-Host "Queue database size: $([math]::Round($queueDb.Length/1GB,2)) GB"2)) GB"
}

# If queue is large, remove expired/stuck messages
Get-Queue | Where-Object { $_.MessageCount -gt 100 } | ForEach-Object {
    Write-Host "Processing queue: $($_.Identity) with $($_.MessageCount) messages"$_.MessageCount) messages"

    # Remove messages older than 2 days with failures
    Get-Message -Queue $_.Identity |
        Where-Object { $_.DateReceived -lt (Get-Date).AddDays(-2) -and $_.LastError -ne $null } |
        Remove-Message -Confirm:$false -WithNDR:$false
}

# Force queue database maintenance
Write-Host "Restarting transport for database compaction..."
Stop-Service MSExchangeTransport -Force
Start-Sleep -Seconds 10
Start-Service MSExchangeTransport

# Check for Event ID 15006 (Normal pressure restored)
Get-WinEvent -FilterHashtable @{
    LogName = 'Application'
    ProviderName = 'MSExchangeTransport'
    Id = 15006
    StartTime = (Get-Date).AddMinutes(-30)
} -MaxEvents 5 | Select-Object TimeCreated, Message

# Verify resource utilization is normal
[xml]$bp = Get-ExchangeDiagnosticInfo -Process EdgeTransport -Component ResourceThrottling
$bp.Diagnostics.Components.ResourceThrottling.ResourceTracker.ResourceMeter |
    Select-Object Resource, Pressure | Format-Table

# Check queue processing resumed
Get-Queue | Measure-Object -Property MessageCount -Sum |
    Select-Object @{N='TotalQueued';E={$_.Sum}}

# Send test email and verify delivery
Send-MailMessage -From "admin@domain.com" -To "testuser@domain.com" -Subject "Back Pressure Test" -Body "Mail flow restored" -SmtpServer localhost

# Set reasonable message size limits
Set-TransportConfig -MaxReceiveSize 25MB -MaxSendSize 25MB

# Configure protocol log retention
Set-TransportService -Identity $env:COMPUTERNAME -ReceiveProtocolLogMaxAge 7.00:00:00 -SendProtocolLogMaxAge 7.00:00:00 -ReceiveProtocolLogMaxDirectorySize 500MB -SendProtocolLogMaxDirectorySize 500MB

# Set message tracking log limits
Set-TransportService -Identity $env:COMPUTERNAME -MessageTrackingLogMaxAge 30.00:00:00 -MessageTrackingLogMaxDirectorySize 1GB