Hello, Last year, I had a first attempt to get federated trust working. After about a month or 2 troubleshooting with Microsoft support, everything was working fine. However, the customer decided not to use the solution at the time. Now, they decided they wanted to give it another shot, so I'm trying to get things working again. The certificate (signed by GoDaddy) is expired, but the Exchange Management console doesn't give any warnings when modifying the Federation Trust (I tried to replace the expired GoDaddy cert by a valid cert signed by GeoTrust, but this doesn't work, the cert is not valid according to MS Live servers). When I try to use the federation trust, it's not longer exchanging data between the organizations (no free/busy info available). Will it help to replace the expired certificates? Or is anything else going on... Thanks for the help, Ben

Did you try test-federationtrustcertificate or test-federationtrust cmdlets? Maybe some other problems you have.Regards, Konrad Sagala, MCT, MCSE+M, MCITP: Exchange 2007/2010

Thanks for your reply. When I execute the test-federationtrust cmdlet, I get an error on the OrganizationCertificate test, so I'll better replace those certificates with valid onces :)

Hi Ben, Microsoft recommend using a self-signed certificate to establish a federation trust with the Microsoft Federation Gateway. Understanding Federation http://technet.microsoft.com/en-us/library/dd335047.aspx And I would suggest you recreate the federation trust after you replace the old certificate.Frank Wang TechNet Community Support