The Exchange Microsoft Remote Connectivity Analyzer has been an essential tool for Exchange administrators since it’s initial release.  This site will attempt to connect to your environment through a variety of methods to help you ensure all is well, or troubleshoot issues related to client connectivity. 

If you haven’t seen this tool, you should definitely check it out:

http://www.TestExchangeConnectivity.com (or the short link: http://exrca.com)

Last week, Microsoft updated this tool to include support for Office 365.  While you wouldn’t actually be troubleshooting Microsoft’s Exchange environment, this new tab allows you to validate your URLs and configurations related to the “Rich-Coexistence” scenario.

Another interesting fact: Microsoft announced plans to incorporate other products into this tool, beyond Exchange Server. 

For a complete list of changes in this version, see the release notes.