I have 2 standalone Exchange servers one 2007 and one 2010. We are upgrading to 2010 but want to be sure the 2010 server is fully updated and working before swapping the 2010 into place as the main server and dropping the 2007 to secondary. Right now I have about 80% of everything set up and working but I cannot get mail to flow from the 2010 to the 2007 server. 2007 to 2010 works fine. So basically any test accounts I migrate over can't mail to anyone else in the domain. Eventually we will swap the 2 servers around and i'm worried we will have the same problem in reverse. It appears that email to outside is working from both servers we use FOPE so all of our outbound email goes through a smart connector to the exchange servers. The 2010 is not registered with FOPE so the messages are not actually sent but the test messages we sent outbound are sitting in the queue for that connector. The internal messages are sitting in a queue called "hub version 8". Both of those connectors have a delivery type of "SMTP relay in active directory site" and relaying is open to the 2007 server and there is a receive connector open for the network the 2010 server is on. Here is what the currently delayed message says: From Address: Test.user2@xzy.com Status: Ready Size (KB): 8 Message Source Name: FromLocal Source IP: 255.255.255.255 SCL: -1 Date Received: 6/21/2011 12:08:20 PM Expiration Time: 6/23/2011 12:08:20 PM Last Error: 400 4.4.7 Message delayed Queue ID: EXCHANGE\8 Recipients: cm@xyz.com Just to make sure this is clear the 2007 server is currently the front end server while we test. The mail flows from 2007 to 2010 fine but not from 2010 to 2007.

Hi, Are Exchange 2007 and Exchange 2010 in the same domain? Is there any Edge Server? If so, I suggest you refer to the following article to create a new Send Connector. http://64.4.11.252/en-us/library/gg981528.aspx If the issue persists, please refer to the following steps to collect the related log file and post it here. Enable SMTP Log --------------- 1. In the console tree, expand Organization Configuration, and select Hub Transport. 2. In the action pane, click on Sender Connectors and right click on send connector and then click on properties. 3. Select “Verbose” under “Protocol logging level” and then click ok. Then, you can find the logs from the following location. Collect SMTP log ----------------- Open the folder on the Hub Server,: C:\Program Files\Microsoft\Exchange Server\TransportRoles\Logs\ProtocolLog\SmtpSend. Thanks. Novak Wu TechNet Subscriber Support in forum If you have any feedback on our support, please contact tngfb@microsoft.com Please remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.

Yes they are in the same domain but on separate subnets. No this is a single server setup there are no edge servers. I will post the logs when I get in to the office.

Ok so there is no send connector between our Exchange servers which is what I wondered if there needed to be but since email is flowing from 2007 to 2010 I was not sure... If there needs to be one I'm also not sure how it would be created (as in what needs to be in it, I know how to create one). The only send connectors we have are to a special fax server, a unix server, and our outbound through forefront. I also added my 2010 server to the allowed servers on FOPE and mail is still not going through them nor does it show in the logs for that send connector although it is sitting in the queue named for it.. These send connectors were all picked up from the original 2007 working in production mail server. None were created on 2010. Both queues (out through FOPE, and hub transport 8) are showing an error of 451 5.7.3 Cannot achieve Exchange server authentication

Ok I figured it out. I have receive connectors on each of my subnets and none of them have "Exchange server authentication" enabled. I created a new receive connector specifically for the IP the 2010 server is on and set it as internal with TLS and exchange server authentication. Now mail is flowing internally and externally. That last error gave me the answer I had just missed it before.