SMTPSEND.DNS.MxLoopback error sending mail between organisations


  • Hi,

    I'm getting a strange error when organisations try to send mail to each other. I'm using Exchange 2010 SP1 in /hosting mode. Sending mail to and from external domains works fine, as does sending mail within the same organisation. I've checked the MX records and they all appear to be fine. Strangely, I'm sure this was all working OK yesterday.

    Is the DNS loopback error a red herring?




    Diagnostic information for administrators:

    Generating server: (domain).com
    #554 5.4.4 SMTPSEND.DNS.MxLoopback; DNS records for this domain are configured in a loop ##

    Tuesday, January 25, 2011 11:38 AM

All replies

  • Tuesday, January 25, 2011 3:08 PM
  • Hi -

    Im having the same issue. How did you solve this?

    kind r



    Friday, January 28, 2011 11:05 PM
  • Not ideal, but I did this:


    new-SendConnector -Name 'TenantedOrgInternalRouting' -Usage 'Internal' -AddressSpaces ';1',';1',';1' -IsScopedConnector $false -DNSRoutingEnabled $false -SmartHosts '[]' -SmartHostAuthMechanism 'None' -UseExternalDNSServersEnabled $false -SourceTransportServers 'Exchange'


    You need to list all SMTP domains like in the example above. This will make e-mails between them be routed internally. I only have about 5 or 6 organisations so this wasn't too much bother. I expect for larger tenanted servers you'd need something a little better.


    Monday, January 31, 2011 1:01 PM
  • same problem here, and the same powershell command does indeed work

    but i'm also wondering, today i have 5 customers, no problem, but what when i have about 100 ???

    is there a way to make a powershell "script" to list and add all the hosted domains?

    or better, a way to make websitepanel do this automatically when adding/removing domains?

    Tuesday, October 18, 2011 9:05 PM
  • found this on microsoft explanation:


    If you have numerous values for a multivalued property, you may not want to retype all of the values just to add another value.
    To avoid that, you can make use of temporary Shell variables. The following example also adds the address
    space with a cost of 10 to the "Connection to" Send connector using a temporary variable called
    $ConnectorConfiguration = Get-SendConnector "Connection to" $ConnectorConfiguration.AddressSpaces += ";10" Set-SendConnector "Connection to" -AddressSpaces $ConnectorConfiguration.AddressSpaces

    does anybody know how to make a powershell script with that? maybe asking for typing the domain when the script is run?

    Tuesday, October 18, 2011 9:14 PM
  • Worked a treat, thanks .. ..  also, helped me out with another problem I had sending to Hotmail from one of my servers.. now routing outbound hotmail emails through a smart host
    Wednesday, February 01, 2012 12:09 AM