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550 5.7.1 <email.address> Relaying denied. IP name lookup failed [10.0.3.57]

    Question

  • Here I am @ midnight trying to figure out something that was working before we changed the Subnet Mask and IP Address on our Exchange 2007 server.

    We send emails from our shipping computer to our customers when their order ships.  We send them internally to our Exchange server from the shipping software.  Authentication is in the software and has been working fine until we tried to get all our servers to the same subnet mask.  Some of them were 255.255.0.0 and we are going to 255.0.0.0 with Class A IP Addresses.

    when we changed the subnet mask on the server, we changed the IP.  We put the new IP in the software and started getting the above messages on all our emails sent to the Exchange server.  the IP Address is the IP Address of the sending PC.

    I've flushed, DNS, flushed ARP cache, rebooted the server, rebooted the PC, rebooted the DC, deleted old DNS entries, etc, etc, etc.

     

    Any ideas?  I need some sleep ... :-)

     

     

    Thursday, February 02, 2012 5:06 AM

All replies

  • I can't tell from the above if this is something you changed during your troubleshooting.  But you will have had to tell your E2007 server that the old IP address is allowed to relay through it (by default nothing can).  Did you change that configuration when you changed the IP address?  Or is it configured so that any source that can authenticate is allowed to relay through it?
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    Thursday, February 02, 2012 1:57 PM
  • Is one of your receive connectors allowed to accept connections from that IP address?
    Thursday, February 23, 2012 8:37 PM