Me and Doc worked on a script a while back that "kind of" does what you want... its definately not the most efficient way to do it, but at the time, I think it was all that was needed.

MX Record lookup help

I modified the MailServerUp function (discussed in the above thread) into the code below. Requires EndProcess() UDF.

Code:
 
Function TNServerUp($server,$port)
  Dim $output,$,$fh,$line,$path
  $output='%temp%\output.txt'
  If Exist($output)
    Del $output
  EndIf
  Run '%comspec% /c telnet -f ' + $output + ' ' + $server + ' ' + $port
  Sleep 2
  $=EndProc('telnet.exe')
  Sleep 1
  $fh=FreeFileHandle()
  If Open($fh,$output)=0
    $line=ReadLine($fh)
    While @ERROR=0
      If Left($line,3)=220
        $TNServerUp=1
      EndIf
      $line=ReadLine($fh)
    Loop
    $=Close($fh)
  EndIf
  If Exist($output)
    Del $output
  EndIf
EndFunction