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  • SMTP banner (validity)

    My exchange server recently started getting bounce backs from @sbcglobal.net. The bounce back is a very generic message and I have confirmed that I am not on the blacklist.
    I ran the DNSstuff.com Mail Server Test Center and everything checks out fine BUT when i run the Domain Doctor Test i fail on SMTP Greeting. The failed text is as follows:

    SMTP greeting:
    Checks the SMTP greeting for validity

    Results:
    No A records found matching banner text for following servers, and banner is not an address literal. RFC5321 requires one or the other (should not be a CNAME). If this is not set correctly, some mail platforms will reject or delay mail from you, and can cause hard to diagnose issues with deliverability. Mailserver details:

    6x.9x.9x.3x : - 220 barracuda.company.com ESMTP (0ce79a530c03423a7a525cbf52afabc1)

    Any help on this issue would be greatly appreciated!



  • #2
    Re: SMTP banner (validity)

    The error means what it says.
    You have configured the appliance with a host name, the host doesn't exist in public DNS. Very common antispam measure.

    You need to change the banner settings in whatever is delivering email to the Internet (a Barracuda I guess) to match the host name for the IP address and ensure that you have a PTR that also matches. The PTR (aka reverse DNS) is set by your ISP.

    Simon.
    --
    Simon Butler
    Exchange MVP

    Blog: http://blog.sembee.co.uk/
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    Sembee is a registered trademark, used here with permission.

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    • #3
      Re: SMTP banner (validity)

      Simon,

      Thanks for your reply.

      I had actually already created an A record (Host - barracuda.company.com and # ip - my static IP) - on Network Solutions before your reply and that took care of the error message I was getting from dnsstuff.com. about my SMTP banner BUT emails to sbcglobal.net continue to fail. I get the bounce back within seconds. The NDR is as follows:

      The message cannot be delivered due to a configuration error on the server. Please contact your Administrator.
      <RAMxxx.xxxEXCHANGE.local #5.3.0 smtp;553 5.3.0 nlpi120 DNSBL:RBL 521< 6x.xx.x2.3x >_is_blocked.__For_information_see_http://att.net/blocks>




      Is this a logical name issue? Should my FQDN be in the error message?..like email.mycompany.com or something similar.


      Thanks in advance for any help.

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      • #4
        Re: SMTP banner (validity)

        so you've created both the resource records sembee mentioned... have you given it the up-to-three-days that DNS can take to fully propagate ?
        have you done an open relay test ?

        you may need to speak to ATT and get yourself removed from their blacklist
        Please do show your appreciation to those who assist you by leaving Rep Point https://www.petri.com/forums/core/im.../icon_beer.gif

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        • #5
          Re: SMTP banner (validity)

          According to that rbl code your system has been detected as spam by ATT.
          That could well not be the case and they are notorious for being unforgiving to missconfigurations so make sure your smtp banner matches the rDNS as suggested.
          If you have a barricuda device make it's configured there the same as your ptr record.
          Caesar's cipher - 3

          ZKHQ BRX HYHQWXDOOB GHFLSKHU WKLV BRX ZLOO UHDOLVH LW ZDV D ZDVWH RI WLPH!

          SFX JNRS FC U6 MNGR

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