I have 2 Exchange servers, one in NY and one in ZH. I have user mailboxes on both servers and they communicated just fine within our WAN (via a VPN). Mails pass freely between the two sites without a problem. The users all have a standard email addresses, with multiple aliases. All user's email addresses are set to a single standard address of companyname.com.
Until yesterdayeverything was working fine. One of the servers got put on a RBL list and we went and addressed the problem and had the server removed from the list. During that time, however, we set up the server to send emails via a smarthost that our security providers had set up for us (for other firewall and vpn purposes). There was an interesting side effect which was that this server was set to route all traffice that goes to companyname.com to the NY server and all traffice that goes to companyname.ch to the Zurich server. Problem is, as mentioned above, all users in the company have default email address set in Active Directory as companyname.com. So all mails being sent to Zurich users were set to STMP queue and sending to zh-exchange.companyname.com (which is resolved correctly from the Exchange server, mind you). When the virtual SMTP queue hit the smarthost, the smart host saw that the address was companyname.com and rerouted the mails back down to the NY server. The STMP server queue never got an ack so it had the messages set to retry and that's how I found it this morning.
Removing the smarthost cleared the queue without problems.
My question: Is there a way to set the smarthost for external emails and set up a route for internal, WAN servers where mails will not be sent via smarthost first. As I understand it, addresses are resolved either via DNS or smarthost. If you define nothing, uses DNS, which is why this worked before. If you define smarthost, ALL messages travel out via the smtp connector through the smarthost.