Routine Maintenance?

We are running Novell Data Synchronizer Version: 1.2 Build: 730 and it has been working pretty well for the past several months. We have around 140 users currently, but the server itself is on robust hardware (8GB Ram, Xeon 2.8ghz dual quad cores). That being said, we have begun getting sporadic reports of delayed delivery of e-mail to devices (by a few hours or so). I personally have not observed this with any of my devices, but I've seen it on a few of my coworkers'. There doesn't appear to be any rhyme or reason for it (I've seen it happen to someone on the same PO and device as me). We've tried a reboot, but the problem remains.

Is there any maintenance I should be running (db optimization, cache flushing, etc) that could potentially help this problem?