smtp-test.ps1

# This is just a generic test message; get's split into an array of commands
##$Global:defaultBody = Get-Content .\EmailMessage.txt

<#
  A DNS Name resolving function
  Designed to be flexible, and work with a list of hostnames
  Can use a specific DNS server/s, or use the one for local interfaces
  Also allows for Type/s, or ALL (either text or * character)
#>
function Get-DNSResolved {
  [cmdletbinding()]
  param(
    [Parameter(Mandatory=$true, Position=0, ValueFromPipeLine)]
    [ValidateNotNullOrEmpty()]
    [string[]]
    $Hostname,
    [Parameter(Mandatory=$false, Position=1)]
    [ValidateNotNullOrEmpty()]
    [string[]]
    $Server,
    [Parameter(Mandatory=$false, Position=2)]
    [ValidateSet("UNKNOWN", "A_AAAA", "A", "NS", "MD", "MF", "CNAME", "SOA", "MB", "MG", "MR", "NULL", "WKS", "PTR", "HINFO", "MINFO", "MX", "TXT", "RP",
    "AFSDB", "X25", "ISDN", "RT", "AAAA", "SRV", "DNAME", "OPT", "DS", "RRSIG", "NSEC", "DNSKEY", "DHCID", "NSEC3", "NSEC3PARAM", "ANY", "ALL", "WINS",
    "*", ignorecase=$true)]
    [string[]]
    $Type = @("A")
  )
  begin{
    if($type -contains "*"){$Type = @("ALL")}
    $results = @()
  }
  process{
    foreach($hn in $hostname){
      foreach($typ in $type){
        if($null -eq $server -or $server -eq @()){
          $results += Resolve-DNSName -Name $hn -Type $Typ
        }
        else{
          foreach($serv in $server){
            $cnt = $results.count
            $results += Resolve-DNSName -Name $hn -Type $Typ -Server $serv
            $results[(($results.count - $cnt) * -1)..-1] | ForEach-Object{$_.Name += " ($($serv))"}
          }
        }
      }
    }
  }
  end{
    return $results
  }
}

# No TLS / SSL support yet...
function Run-SMTPTest {
  [cmdletbinding()]
  param(
    [Parameter(Mandatory=$true, Position=0, ValueFromPipeLine)]
    [ValidateNotNullOrEmpty()]
    [string[]]
    $Recipient,
    [Parameter(Mandatory=$false, Position=1)]
    [ValidateNotNullOrEmpty()]
    [string]
    $Subject = "SMTP Testing - IT Administration",
    [Parameter(Mandatory=$false, Position=2)]
    [ValidateNotNullOrEmpty()]
    [string]
    $Sender = "SMTPTest@FakeDomain.com",
    [Parameter(Mandatory=$false, Position=3)]
    [ValidateNotNullOrEmpty()]
    [string]
    $Server = "",
    [Parameter(Mandatory=$false, Position=4)]
    [ValidateNotNullOrEmpty()]
    [int32]
    $ServerPort = 25,
    [Parameter(Mandatory=$false, Position=5)]
    [ValidateSet("Inbound","INB","IN","OUT","OUTB","OUTBOUND", ignorecase=$true)]
    [string]
    $Direction = "Inbound"
  )
  # Need to figure out the possible mode we are going for...
  begin{
    # Figure out whether inbound / outbound (Inbound meaning you focus on recipient end / sending as a server, or Outbound as in connecting
    # to the desired server for sending - I.e. Exchange Online)

    # Here is the list of commands - this is a skeleton for testing.DESCRIPTION
    # Going to have to set this with replace portions - can rebuild the proper message during each process
    #$(if($spfcommands){$spfcommands}else{""})
    $commandsTemplate = @"
EHLO [DOMAIN][SPF]
MAIL FROM:<[SENDER]>
RCPT TO:<[RECIPIENT]>
DATA
<MESSAGE>
escape
"@

    $messageTemplate = @"
Date: [DATE]
To: [RECIPIENT]
From: SMTP Testing <[SENDER]>
Subject: [SUBJECT]
Message-ID: <b43b694073f6450e95dc92d566f11ce7@_>
X-Mailer: SMTP-Tester
MIME-Version: 1.0
Content-Type: text/plain; charset=iso-8859-1

[BODY]

.
"@

  }
  process{
    ## Process will involve handling the connection, and going through a specific series of commands up until the attempt
    ## Of actually sending the email
    foreach($recip in $Recipient){
      $SenderDomain = ($Sender -split "@")[-1]
      $RecipientDomain = ($recip -split "@")[-1]
      if($direction.ToUpper() -in @("INBOUND","INB","IN")){
        $domain = $RecipientDomain
      }else{
        $domain = $SenderDomain
      }
      # Since a custom server is not defined, let's just set it to what the MX record of the Sender's domain
      # NOTE: it will likely return as multiple IPs depending on the server; so logic should be set to try one, and then the next...
      #       until either one works or all fail
      if($Server -eq "" -or $null -eq $Server){
        $Server = (Get-DNSResolved (Get-DNSResolved $domain -Type MX).NameExchange).IPAddress[0]
      }
      ## Format for Header
      $DateF = ((Get-DAte -Format "ddd, d MMM yyyy H:mm:ss ") + (((Get-Date -Format "zzz") -split ":") -join ""))
      $commands = $commandsTemplate
      $message = $MessageTemplate
      $commands = $commands -replace "\[DOMAIN\]",$SenderDomain
      $commands = $commands -replace "\[SPF\]",$null
      $commands = $commands -replace "\[SENDER\]",$Sender
      $commands = $commands -replace "\[RECIPIENT\]",$recip
      $message = $message -replace "\[SENDER\]",$Sender
      $message = $message -replace "\[RECIPIENT\]",$recip
      $message = $message -replace "\[DATE\]",$DateF
      $message = $message -replace "\[SUBJECT\]",$subject
      $message = $message -replace "\[BODY\]","Testing email"
      $commands = $commands.Split([Environment]::NewLine)
      $message = $message.Split([Environment]::NewLine)
      ## Get TCP connection Going
      $commandCount = 0
      Write-Host $server -ForegroundColor Green
      $tcp = New-Object System.Net.Sockets.TcpClient($server,$serverport)
      $tcpstream = $tcp.GetStream()
      $writer = New-Object System.IO.StreamWriter($tcpstream)
      $reader = New-Object System.IO.StreamReader($tcpstream)

      while($tcp.connected)
      {
        $reply = ""
        $reply += ([char]$Reader.Read())
        while(($reader.Peek() -ne -1) -or ($tcp.Available)){
          $reply += ([char]$reader.Read())
        }
        switch -Wildcard ($reply){
            "5*" {Write-Host $reply -ForegroundColor Red -NoNewLine; Break}
            "2*" {Write-Host $reply -ForegroundColor Green -NoNewLine; Break}
            Default{
                Write-Host $reply -NoNewLine
            }
        }
        # Let's just completely close connection if error
        if($reply -like "5*"){break}
        if($tcp.connected)
        {
            $command = $commands[$commandCount]
            if($command -eq "escape"){break}
            if($command -eq "<MESSAGE>"){
              foreach($msg in $message){
                if($tcpstream.DataAvailable){$reader.ReadLine()}
                Write-Host $msg -ForegroundColor Yellow
                $writer.WriteLine($msg)
                $Writer.Flush()
              }
            }else{
              Write-Host $command -ForegroundColor Yellow
              $writer.WriteLine($command)|Out-Null
              $Writer.Flush()
            }
            $commandCount++
        }
      }
      $reader.Close()
      $writer.close()
      $tcp.Close()
    }
  }
  end{

  }
}