How to Enable Debug Level Logging
If you are experiencing mail flow issues in Exchange Server 2003 and want to view all events as part of your troubleshooting effort, you can modify a registry key to set event logging to level 7, the debugging level, which is the highest level.
Before You Begin
This topic contains information about editing the registry.
Warning
Incorrectly editing the registry can cause serious problems that may require you to reinstall your operating system. Problems caused by not editing the registry incorrectly may not be able to be resolved. Before editing the registry, back up any valuable data.
Procedure
To enable logging at the debugging level
Start Registry Editor.
In Registry Editor, locate and then click the following registry key:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\
MSExchangeTransport\Diagnostics\SMTP Protocol
Set the value to 7, and then click OK.