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"550 Access denied - Invalid HELO name" when emails are sent to certain domains

Hi,

I've noticed recently that when emails are being sent to certain domains from our Exchange Server they are failing a HELO check. Our emails our going through the Astaro SMTP proxy, all emails going out from the proxy are doing so via one IP address and I have checked that this IP address is not blacklisted anywhere. Also the the IP address associated with sending out email has a public DNS record.

Any help appreciated.

Thanks


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  • Turboizzy, I would change the hostname back to Astaro and just put the FQDN where Scott suggests.  

    Here's the real problem - you can't have RDNS unless you have a fixed IP; either that or you need to change the SMTP hostname every time you get a new IP.

    DynDNS can sell you the service I suggested, and that will resolve your issue; there are other suppliers of this same service, but no free ones.  The alternative is to stop using DynDNS altogether and get a fixed IP.

    Cheers - Bob
     
    Sophos UTM Community Moderator
    Sophos Certified Architect - UTM
    Sophos Certified Engineer - XG
    Gold Solution Partner since 2005
    MediaSoft, Inc. USA
  • Bob, Izzy says he has a business connection with 6 static IPs; if it works like it works here in the U.S, his ISP will configured RDNS for him, and his problem should be resolved.

    CTO, Convergent Information Security Solutions, LLC

    https://www.convergesecurity.com

    Sophos Platinum Partner

    --------------------------------------

    Advice given as posted on this forum does not construe a support relationship or other relationship with Convergent Information Security Solutions, LLC or its subsidiaries.  Use the advice given at your own risk.

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  • Bob, Izzy says he has a business connection with 6 static IPs; if it works like it works here in the U.S, his ISP will configured RDNS for him, and his problem should be resolved.

    CTO, Convergent Information Security Solutions, LLC

    https://www.convergesecurity.com

    Sophos Platinum Partner

    --------------------------------------

    Advice given as posted on this forum does not construe a support relationship or other relationship with Convergent Information Security Solutions, LLC or its subsidiaries.  Use the advice given at your own risk.

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