I have a SBS Server 2008 R2 that has an expired certificate. Every time one of the users logs into their 2010 Outlook it gives them the error attached. I have followed online guides to create a new self signed certificate using comandlets in the power shell prompt but I keep getting an error that is telling me there is no such command. This is one of the commandlets that I have run: Get-ExchangeCertificate | List. I am running Exchange server 2007 which was configured during the installation process. As was the original self signed certificate. Any help would be much appreciated.