Several users reported that they could not turn on or off their Out of Office reply using either Microsoft Outlook 2007 or 2010. They did not have any problems turning on or off their OOF reply using Microsoft Outlook Web App. When they attempted to turn on or off their Out of Office reply, they received a Your automatic reply settings cannot be displayed because the server is currently unavailable. Try again later. error message. If you are using Outlook 2007/2010, the first thing you need to do to start troubleshooting the problem is to use the Outlook Test E-mail AutoConfiguration option (hold the Ctrl button down and right-click the Outlook icon in the desktop tray to access the option). Uncheck the Use Guessmart and Secure Guessmart Authentication checkboxes and click Test. Review the Results and Log tabs for more information to start isolating the problem. In addition, you can use the following PowerShell commands to verify if anyone inadvertently changed the Exchange Web Services or AutoDiscover Service Internal Urls for any of your CAS servers: Get-WebServicesVirtualDirectory -Server <CAS server name> fl *Url Get-ClientAccessServer | fl *Uri Here is what we did to troubleshoot and resolve the issue, we used Internet Explorer to connect to Exchange Web Services on each of the Client Access Servers in our environment. The URL to connect to Exchange Web Services is https://<FQDN of CAS server name>/ews/exchange.asmx When you successfully connect, you should see your output similar to the following. When we attempted to connect to the Exchange Web Services URL on one of our Exchange 2010 Client Access Servers, we received a HTTP Error 503. The service is unavailable error message. After logging into the Exchange 2010 Client Access Server, we noticed several Exchange Application Pools had stopped in IIS. After we restarted the Application Pools, users were able to successfully turn on or off their Out of Office reply without any issues.