Microsoft Exchange Remote Connectivity Analyzer

“The Remote Connectivity Analyzer is a web based tool that's designed to help IT administrators to troubleshoot connectivity issues with their Exchange Server deployments. It allows administrators to test connectivity to their Exchange domains remotely from outside of their organizations internal networks. In order to use this tool, you must enter the credentials of a working account from the Exchange domain to be tested. To avoid the potential risk of working credentials being exploited and therefore compromising the security of your Exchange environment, we strongly recommend that you create a test account for the purpose of using this tool, and delete this account immediately after you have completed the connectivity testing.”