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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
    Bob, Izzy says he has a business connection with 6 static IPs

    Thanks, Bruce, I missed that.  It's strange though that he would use the DynDNS service for inbound mail.  Few spams get past the SMTP time before they are rejected, so I don't see how the DynDNS service would eliminate much bandwidth usage.  Thoughts?

    Cheers - Bob
     
    Sophos UTM Community Moderator
    Sophos Certified Architect - UTM
    Sophos Certified Engineer - XG
    Gold Solution Partner since 2005
    MediaSoft, Inc. USA
  • 0 in reply to BAlfson
    Some folks just like dyndns [:)]

    The OP hasn't responded in a while, but I bet their issue was rectified once they configured the appropriate PTR record.  About twice a month I'll have a potential customer, or an existing customer"s client, pop up with a mail issue due to missing RDNS info.

    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.

Reply
  • 0 in reply to BAlfson
    Some folks just like dyndns [:)]

    The OP hasn't responded in a while, but I bet their issue was rectified once they configured the appropriate PTR record.  About twice a month I'll have a potential customer, or an existing customer"s client, pop up with a mail issue due to missing RDNS info.

    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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