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

turboizzy
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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  • 0
    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
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  • 0
    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
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  • 0 in reply to BAlfson
    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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