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I'm trying to set up PHP on a Windows Server 2008 machine running both IIS7 and Exchange 2010, and no matter what I do, it will not relay messages outside of the domain.

I.e.: I telnet to localhost 25, do the HELO/MAIL FROM:/RCPT TO: dance. Any domain ending in my local domain works; any with elsewhere as domain receive a 550 5.7.1 Unable to Relay error.

If I set * as an Accepted Domain, everything starts working, mails relay, all of it works great. However, this is clearly problematic -- I'd really like to not turn my client's server into an open relay (verified via's relay checking tool).

How does one enable open relaying from only localhost in Exchange 2010?

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up vote 4 down vote accepted

Create a new receive connector. Set the scope to,check the box that says "Externally secured", and allow anonymous connections as well as Exchange Servers. You'd do that in EMS like this:

new-receiveconnector -name LOCALHOST -Usage Custom -authmechanism externalauthoritative -enabled $true -fqdn -remoteipranges -permissiongroups anonymoususers,ExchangeServers -bindings

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No dice; still get the same error. – aendrew Sep 6 '11 at 23:42
Try it with the updated EMS command. I just successfully tested it in my lab running Exchange 2010 SP1 – Jason Berg Sep 6 '11 at 23:44
Also make sure you don't have another receive connector with the same scope. – Jason Berg Sep 6 '11 at 23:44
That totally worked. And I did have a receive connector with the same scope -- apparently there was a SBS Fax Sharepoint there too. Deleting that enabled your command to work beautifully. – aendrew Sep 6 '11 at 23:50
Thankyou thankyou thankyou @Jason for the note about turning off the other connector in the same scope. 24 hours of frustration solved! – LRE Nov 15 '13 at 21:20

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