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SMTP;550 not allowed to send mail SBS 2003

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  • SMTP;550 not allowed to send mail SBS 2003

    Yesterday all of our local users were affected by an SMTP error that prohibited them from sending any external mail. They could mail within the office, and would receive mail from outside, but they were not able to send out.
    I have reset the SMTP controller, and am using a smarthost. Our mail is filtered through postini and we have not changed our MX records.

    After reading here for some common problems I noticed that our IP had been listed on No more funn as a possible spam/blacklist IP. After requesting this be cleared I do not see the blacklist in place this morning. However we are still unable to send out bound mail.
    I have also requested through our ISP that our rdns be modifyed from the generic service address that is provided.

    The specific error is copied below:
    From[email protected]
    To: RobWork Email
    Sent: 4 Dec 2008 07:35
    Subject: Delivery Status Notification (Failure)

    This is an automatically generated Delivery Status Notification.

    Delivery to the following recipients failed.

    [email protected]

    -----Embedded Message-----

    Final-Recipient: rfc822;[email protected]
    Action: failed
    Status: 5.5.0
    Diagnostic-Code: smtp;550 you are not allowed to send mail to <[email protected]>

    We are running SBS 2003 r2 with most updates installed (I have not updated in approximately 1 week.) The sudden stop happened yesterday some time around noon. I was unable to find a reason for the stop in the application log.
    Any help would be immensely appreciated.
    Last edited by crmsmith; 9th December 2008, 16:52. Reason: Removing private info

  • #2
    Re: SMTP;550 not allowed to send mail SBS 2003

    How did you notice you were listed? Was it just on one site or on many? can search a few for you. You may find certain domains will take a while to accept you again or that you are still listed elsewhere.

    Is your firewall locked down so only the server can send out on port 25?

    If your mail goes out to "postini" for filtering (I assume you mean you relay through them) then maybe they are blacklisted? Have you spoken with them about this? They may be blocking you.

    Please read this before you post:

    Quis custodiet ipsos custodes?


    • #3
      Re: SMTP;550 not allowed to send mail SBS 2003

      I found out we were blacklisted while asking our ISP to correct the rDNS records to reflect our domain. The place I looked for the blacklist info was MXtoolbox, and it only returned the blacklist at no more funn.
      The firewall is configured for outbound on 25 and inbound on 110. (To my understanding these settings have not changed since the server was installed in 2004.) I did speak with our account rep technical support for Postini and they did not see any changes that would prohibit us from sending mail.
      When the error began to be reported we were not setup with Postini for our outbound smarthost. Our outbound smarthost was through our ISP. Postini had me reconfigure the smarthost to channel through their filters and we were still unable to send out.


      • #4
        Re: SMTP;550 not allowed to send mail SBS 2003

        SMTP is 25, 110 is POP3 so isn't relevant here.
        You need 25 inbound too! but seeing as you don't have inbound problems I will assume this is there.

        If you have changed your connector to use a smarthost and still have problems then it isn't likely to be a blacklisting.

        Can you telnet out from your Exchange server to port 25 at postini and connect ok?

        Have you installed/altered AV on the Exchange box at all?

        Please read this before you post:

        Quis custodiet ipsos custodes?


        • #5
          Re: SMTP;550 not allowed to send mail SBS 2003

          We haven't changed any of the AV settings (currently using McAfee 8.5i for AV) since it was upgraded back in July.
          I ran the smtpdiag tool and can give those results, but I did not want to post the entire log if without making sure that was ok.
          Connecting to [] on port 25.
          220 ESMTP 4si4930584gxk.36Sent:
 at your service, [my ip address]
          250-SIZE 35651584

          I seem to be able to get out on telnet to postini (at least I get a response from them but outbound mail still bounces back with the 550 error.)