Jason,
You can turn on Macro tracing for this:
Call Control
Conversation State
Call flow
Traces for MWI problems then start new log files.
Make sure your inbox is empty or that all messages are marked read before leaving the office, and in the morning collect AvCsMgr, AvMsgStoreMonitorSvr, AvNotifierMgr files that span throughout the night. The AvMsgStoreMonitorSvr logs will be the first place MAPI notifications appear indicating any new messages, so I'd check for your user name in that file.
Hope that helps,
Brad