Recently a friend reminded me few cases, we were analyzing, while I was working as messaging engineer. We had problems with an application, which was using EWS (Exchange Web Service), trying to get free/busy information from exchange. Then IIS was becoming unresponsive and the only thing we could do was IIS reset. So we used “httperr.log” for the analysis and issue detection. Probably not many of you heard about it, but this log is really useful with issues related to web server.