Re: FW: What the heck? Telnet to SMTP...

  • From: "Paul Lemonidis \(Hotmail\)" <paul_lemonidis@xxxxxxxxxxx>
  • To: "[ExchangeList]" <exchangelist@xxxxxxxxxxxxx>
  • Date: Thu, 28 Jul 2005 17:21:13 +0100

 Hi Chris

Yes. You are right. This is standard for mail servers published through a Cisco 


Paul Lemonidis.
  ----- Original Message ----- 
  From: Chris Wall 
  To: [ExchangeList] 
  Sent: Thursday, July 28, 2005 5:03 PM
  Subject: [exchangelist] FW: What the heck? Telnet to SMTP...

  Never mind -  I think the PIX is the culprit.  Time to have a little talk 
with the Network Admin J


  See here for info -





  From: Chris Wall 
  Sent: Thursday, July 28, 2005 11:59 AM
  Cc: [ExchangeList]
  Subject: What the heck? Telnet to SMTP...


  Hello all,


  I have a weird one here.  I have two SMTP Gateway boxes for our organization. 
 One is Win 2003 Server with IIS and the other is Win 2000 Server with IIS.  
Neither of these servers have Exchange installed, but they do act as Smart 
Hosts for our Exchange 2003 environment.


  I have just found out that when someone (externally) attempts to telnet to 
our SMTP hosts ( and the following appears:




  If I attempt to type 'EHLO' or 'HELO' I receive the following:


  500 5.3.3 Unrecognized command



  If I attempt to telnet to these servers from an internal PC, using the 
internal IP address, I get the standard:


  220 Microsoft ESMTP MAIL Service, Version: 

  1 ready at  Thu, 28 Jul 2005 11:53:55 -0400


  When typing 'HELO' or 'EHLO' I get the normal reply:



  250 Hello []


  Mail is flowing as it should into our organization, but I am unable to 
successfully force a Telnet Session to our servers from an external computer.  
In the past, our servers have responded to telnet requests as if internal, but 
now they respond with '220 *************' etc.  


  What could be causing this since I have not made any changes to the IIS SMTP 


  Any help is greatly appreciated.




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