I've noticed this on several machines, with both 5.02 builds of the ZCO that I have tried, that at random times, Outlook 2007 will stop sending and receiving emails, even if it says it successfully sent and received. Since I have not seen a similar bug in the bugzilla, I wouldn't be surprised if this still occurred in 5.03. This is a very serious issue since users think they are not receiving email when they are. I will get logs the next time I run across the problem.