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Relaying via postfix server works from outlook but not from exchange smarthost

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  • Relaying via postfix server works from outlook but not from exchange smarthost

    I have set up a machine running a basic install of CentOS with postfix.
    I have configured it to allow relaying from certain IP addresses.
    I have set up SPF record and RDNS and so on.

    If I set up an outlook pop account on a remote machine - I use a completely separate email address, say [email protected]

    I then set the outgoing SMTP server to be my postfix smarthost, say mx1.myserverdomain.com

    And I set authentication to none - as I am allowing the communications just by the IP address of this remote client machine.

    It works fine and the email arrives, via the smarthost.

    However, when I impliment the same scenario in exchange 2003 - I create a smarthost and configure it to route mail via mx1.myserverdomain.com with no authentication, it does not arrive, I dont get a bounce back either.

    To further test, I tried via telnet to send from the exchange server, via the smarthost, and doing that seems to work, but then I get a bounce back saying that the message was incorrectly formated.

    I read an article about this and that it was an issue with the from address.
    And if I do the following from telnet:
    ...DATA
    From: <[email protected]
    Subject: test
    data
    .

    Then it arrives correctly!
    I dont understand though, why exchange smarthost is malformating the message, and outlook client is not??
    David Silvester
    Systems Administrator

  • #2
    Re: Relaying via postfix server works from outlook but not from exchange smarthost

    Originally posted by davids355 View Post
    I have set up a machine running a basic install of CentOS with postfix.
    I have configured it to allow relaying from certain IP addresses.
    I have set up SPF record and RDNS and so on.

    If I set up an outlook pop account on a remote machine - I use a completely separate email address, say [email protected]

    I then set the outgoing SMTP server to be my postfix smarthost, say mx1.myserverdomain.com

    And I set authentication to none - as I am allowing the communications just by the IP address of this remote client machine.

    It works fine and the email arrives, via the smarthost.

    However, when I impliment the same scenario in exchange 2003 - I create a smarthost and configure it to route mail via mx1.myserverdomain.com with no authentication, it does not arrive, I dont get a bounce back either.

    To further test, I tried via telnet to send from the exchange server, via the smarthost, and doing that seems to work, but then I get a bounce back saying that the message was incorrectly formated.

    I read an article about this and that it was an issue with the from address.
    And if I do the following from telnet:
    ...DATA
    From: <[email protected]
    Subject: test
    data
    .

    Then it arrives correctly!
    I dont understand though, why exchange smarthost is malformating the message, and outlook client is not??
    What do your exchange tracking logs say? Is the message actually being delivered to the relay?

    Can the exchange server resolve the mx1.myserverdomain.com record to an IP?

    Are you using authentication on your client?

    Comment


    • #3
      Re: Relaying via postfix server works from outlook but not from exchange smarthost

      No authentication on the client, or on the smart host.

      Yes it can resolve the dns name to an ip, and in fact I have successfully telneted from the exchange server to the relay.

      I will check the logs in the morning and see if I can get some additional info.
      Thanks
      David Silvester
      Systems Administrator

      Comment


      • #4
        Re: Relaying via postfix server works from outlook but not from exchange smarthost

        really weird - I could ping mx1.myserverdomain.com from the exchange server and it was returning the correct IP.

        However, when I added the ip ([1.2.3.4]) to the exchange smarthost connector, it all started working!

        I really cant understand what was going on there, maybe exchange is not translating the DNS name?

        Anyway, its working now. delivery is good except for to microsoft domains - they are going into junk, so I think I need to set up DKIM.
        David Silvester
        Systems Administrator

        Comment

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