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problems with NDRs and spam

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  • problems with NDRs and spam


    I have a ISA SERVER 2006 firewall with IIS 6.0 installed and with smpt service. This server is a relay to my MS Exchange server.
    I have a problem with NDRs and spam. This smtp relay is continuously trying to send NDRs to non-existent domains and its queue is growing indefinitely. This is mail's example that my "ISA SMTP relay" is trying to send:

    FROM: [email protected]
    TO: [email protected]
    Subject: Notificación de estado de entrega (Error)

    Esta es una Notificación de estado de entrega generada automáticamente.

    Error en la entrega a los siguientes destinatarios.

    [email protected]

    Are there any way to disable NDRs in the IIS SMTP.



  • #2
    Re: problems with NDRs and spam


    One thing i would do if you are getting this is to first, 'Filter Recipients who are not in the directory' option enable under Messages delivery - Recipient filtering.

    You then need to enable recipient filtering under the SMTP virtual Server.

    What can happen is that people spam your domain by just guessing email addresses, and everytime this happens, your exchange box is trying to send an NDR syaing that that person doesn't exist. If you only allow messages to known recipients this shoudl ease up.

    YOu can also disable NDRs if necessary in the Sender ID filtering tab of the Message delivery options.
    MCSA/MCSE 2000
    MCSA/MCSE 2003

    I love pies.


    • #3
      Re: problems with NDRs and spam

      If you don't have an antivirus&antispam for email gateways products installed on ISA 2006 I don't see why to use it as smart host and not directly publish outside the smtp service of your Exchange. Isa server has a powerful secure Mail server publishing rule. In this way, smtp traffic is protected by ISA and unwanted (spam) emails are blocked directly by the IMF.
      Also, take a look into the smtp tar pitting feature. It is a good spam fighter and it is FREE.
      Csaba Papp
      MCSA+messaging, MCSE, CCNA
      Remember to give credit where credit is due and leave reputation points where appropriate


      • #4
        Re: problems with NDRs and spam

        This is the reason Harry Brelsford recommends not using NDRs at all, so consider switching them off. (Harry writes great books on SBS.)
        Best wishes,
        MCP:Server 2003; MCITP:Server 2008; MCTS: SBS2008