#
# get-wrongsender
#
# Parse Exchange Message tracking to find Sender using a local domain with an invalid sender
# limit to SMTP Receive
#
# Ver 1.1 20140624 FC  initial Version
# Ver 1.1 20140625 FC  MaxDays addiert
# Pending: Output in File

param (
	[string]$lastrunfile = ".\get-wrongsender.txt",
	[int]$maxdays = 1
)

write-host 'Set Scope to forest'
set-ADServerSettings -viewentireforest $true 

[datetime]$lastrun = get-date("01.01.2000")   # initialize
if (test-path $lastrunfile -PathType leaf) {
	write-host 'Loading LastRun from $lastrunfile'
	$lastrun = get-date(get-content $lastrunfile)
	write-host ('lastRun (File):' + $lastrun)
}

# für debuggung
# $lastrun = (get-date).addminutes(-1)
if ((get-date).adddays(-$maxdays) -gt (get-date($lastrun))) {
	write-host ' Apply MayDays Limit'
	$lastrun = (get-date).adddays(-$maxdays)
	write-host ('lastRun (Limit):' + $lastrun)
}


write-host 'Loading local Domainlist'
$domainlist =@{}
foreach ($domain in ( Get-AcceptedDomain)) {
	$domainlist.add($domain.domainname.smtpdomain.domain.tolower(),$true)
}

write-host ('Added Domain:'+$domainlist.count)

write-host 'Processing Message Tracking'

$recipientcache = @{}

$messages = get-transportserver | Get-MessageTrackingLog -Start $lastrun -EventId receive -resultsize unlimited | ?{$_.source -eq "smtp"}
foreach ($message in $messages) {
	[string]$sender = $message.sender.tolower()
	write-host ('Sender:'+ $sender) -nonewline
	[string]$senderdomain = ($message.sender.split('@'))[1].tolower()
	if ($domainlist.containskey($senderdomain)) {
		Write-host ' LocalDomain' -nonewline
		if (!($recipientcache.containskey($sender))) {
			write-host " Lookup" -nonewline
			if ((Get-Recipient $sender -ErrorAction continue) -ne $null) {
				write-host " found" -nonewline
				$recipientcache.add($sender,$true)
			}
			else {
				$error.clear()
				write-host " NOTfound" -nonewline
				$recipientcache.add($sender,$false)
			}
		}

		if ($recipientcache.item($sender)) {
			write-host ' valid sender - OK'
		}
		else {
			write-warning ' invalid sender - Problem'
			$message
		}
	}
	else {
		Write-host ' ExternSender -skip'
	}
}

Write-host ('Last Message:' +$messages[($messages.count -1)].timestamp)
$messages[($messages.count -1)].timestamp.tostring() | out-file $lastrunfile
write-host 'done'