What Is The RUS Doing Now and Why?
In Exchange 2003, you can view the object the RUS is processing by setting Proxy Generation diagnostics to maximum
Using ESM, pull up the server properties of the RUS machine. Choose Diagnostic Logging, MSExchangeSA, Proxy Generation. Set that value to maximum. Now in the event log you will start to see 3006 messages. Each message will contain the object being processed, which polices that apply to the object, the proxies the object has, and the proxies the RUS will apply.
If the RUS is doing a full rebuild, you can see how far along the RUS is, by setting the Address List Synchronization diagnostics to medium.
Using ESM, pull up the server properties of the RUS machine. Choose Diagnostic Logging, MSExchangeAL, Address List Synchronization. Set that value to medium. Now in the event log look for 8329, 8332 and 8330. The RUS logs 8329 at the beginning of a rebuild. 8330 at the end. During the rebuild the RUS will log a 8332 message every 10% of the way( approximately).