Our company provides email marketing services. Our service is hosted and emails are deployed from our IP addresses. Clients use their email address(es) as the "from" address, and typically, as long as they have the SPF record in place that includes our IP addresses, there isn't a problem with deliverability. We have one client that cannot receive emails deployed from our IPs on their internal network when one of their company addresses is the From address. The client is using exchange 2010.
Example: Client deploys an email to recipient: email@example.com From our server (and IP) using their from address: clientServices@theclient.com
-The email is not delivered. -The client has included our SPF in their DNS record -If we use any other sending address from an outside domain, it is delivered without issue.
The client uses Postini, and has indicated that clientServices@theclient.com is white listed there, and the email is not getting caught and quarantined anywhere in Postini, so it appears that it is getting passed through, and dying at the Exchange server level. We don't believe Postini is the problem.
Is there a setting in Exchange that needs to be set for that address, or server wide that would have a positive impact on the scenario described above?