With enabled Exchange Message Tracking you can tell what is going on with your messages. From the information you have included it is tough to trouble shoot. Check out this info on tracking messages.
Message Tracking can be enabled on the Exchange Server object in Exchange System Manager or with the help of System Policies for more than one Exchange Server. You can read more about Implementing Exchange System Policies here.
To enable Exchange Message Tracking, start the Exchange System Manager and navigate to the Server object on which you want to activate Message Tracking.
Now you can enable Message Tracking and Subject Logging. If you enable Subject logging and display, the subject of every message will be displayed in the Exchange Message Tracking Center.
Please note that enabling of Subject Logging can produce some processing overhead on highly used Exchange Servers and you must also ensure that your security policy allows the logging of e-mail subjects.
You must specify the number of days after old logfiles will be deleted.
The Default Logfile directory is c:\program files\ExchSrvr\Servername.LOG.
By enabling Message Tracking, Exchange shares the Message Tracking directory for Administrators only, so you will need to grant read access to the share for users performing Message Tracking.
Now it is time to navigate to the Exchange Message Tracking Center. The Message Tracking Center allows you to track Messages. You can specify the Sender of the Messages and the Recipient of the Message. You can specify the logging time from where you will track messages. After you enter the required information you can click “Find Now”. If your search options are correct, you will see the Messages in the Message Tracking Center.
If you doubleclick the Message a new window with more information about the message will appear. Now you can see the Message Flow in detail. As you can see in this example, the Message was submitted from the Exchange Store, transmitted to the Advanced Queuing Engine routed through the Categorizer and delivered locally to Sean@nwtraders.msft. This example deals with a single Server Message Flow, where it is easy to track where the Message has gone. Message Tracking is more powerful if you track messages in a multi Server scenario or when the message leaves the Exchange organization through a Connector or virtual SMTP server.
Exchange Message Tracking maintains a text logfile for every day. It is simple textfile so you can open the file with notepad or Excel for advanced analysis.