Just recently we started experiencing inbound routing issues. Email adddressed to [email protected] is intermittantly translated to [email protected]. This is happening for several users and, as stated, is intermittant.

I don't know where to start looking for the solution. Is this an Exchange issue? A DNS issue?

We have a single Exchange server inside our network with an FQDN of server.domain.local with a single SMTP Virtual Server. The Advanced properties of the Delivery tab of the Virt Server has an empty Masquerade Domain textbox and the value for the FDQN text-box is set to the domain itself, domain.com.

The DNS record for domain.com is a CNAME entry referencing www.domain.com. Is this somehow related to the problem?

I checked the headers of the inbound messages that generated NDRs as a result of being sent to [email protected] and nowhere in the header is www.domain.com mentioned.

To make my life even more difficult, we use Postini as a third-party SPAM filtering service. Our MX records point to the Postini servers and Postini delivers the messages to our server. Perhaps it is Postini that is mucking things up?

sigh I'm having trouble with this one and the intermittent aspect is making it that much more difficult for me.

Any ideas?