Spam Filter/Restricting SMTP Traffic

We use a third party spam filter called Postini.  All of our inbound and outbound traffic goes through this company's servers.  Our MX record points to them, they filter and send the mail to us.  In their setup instructions, it states that I need to lock down my e-mail relay to restrict inbound SMTP traffic to ONLY their server's IP addresses.

I am very familiar on how to set the relay restrictions in Server 2003 with Exchange 2003 but now we are using Server 2008 Standard with Microsoft Exchange 2010 installed.

I can't find anyone who knows how to do that in Exchange 2010 with a Hub Transport.
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It is in the receive connector.

Exchange Management Console --> Server config --> Hub transport --> Receive connector.

Select the one for inbound mail and go to network and then remote IP ranges, set to only those ranges specified.

See here for background info:

If it the remote network settings section.

qualityipAuthor Commented:
Okay, perfect. I had it configured properly but we keep receiving tons of 400 errors.
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400 is a transient failure. What do you mean that you are receiving 400 errors? Do you mean when sending outbound mail or are you seeing these in the queues on exchange?

qualityipAuthor Commented:
The issue was resolved. The error was occuring because we had an old alias domain configured in Postini. The e-mail to that domain was accepted into our network as it was coming from Postinibut Exchange 2010 was not configured to accept e-mail from the domain. The 400 errors were a result of the bounceback messages after our Exchange server declined to relay the e-mail.
It's odd that 400 errors were generated, was there any description with the error? Usually not able to relay is a 5xx (usually 5.1.7)

qualityipAuthor Commented:
We originally noticed undeliverable 400-error messages in our outgoing message logs in Postini:

2010/05/10 05:47:18      
IP: ---
Disposition:f      Subject:Undeliverable: New Job: Carport Construction in Hudson
Glad you got it fixed,


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