A valid third-party certificate is imported into a Microsoft Exchange Server 2007 or 2010 Client Access server (CAS). Then, the following status message is displayed in the Exchange Management Console:

The certificate status could not be determined because the revocation check failed.

If you run the Get-ExchangeCertificate cmdlet in the Exchange Management Shell, you receive the following status for the third-party certificate:

Exchange 2010:

Status: RevocationCheckFailure

Exchange 2007:

Status: Unknown

However, if you click the Certificate Revocation List (CRL) link that is specified on the certificate, you can still access the third-party certificate through the Exchange server. 

Why?

This issue occurs because Exchange Server 2007/2010 uses Microsoft Windows HTTP Services (WinHTTP) to manage all HTTP and HTTPS traffic, and WinHTTP does not use the proxy settings that are configured for the Internet browser.

To view the WinHTTP proxy settings, at a command prompt, run the following command:

netsh winhttp show proxy

Resolution

To resolve this issue, you must configure the WinHTTP proxy setting and the server FQDN in the WinHTTP bypass list.

Note: If you do not configure both the proxy setting and the server FQDN in the WinHTTP bypass list, the Exchange Management Shell and the Exchange Management Console cannot contact the Remote PowerShell.

To resolve this issue, open a command prompt, type the following command, and then press ENTER:

netsh winhttp set proxy proxy-server="http=myproxy" bypass-list="*.host_name.com"

The myproxy placeholder represents the proxy server name, and host_name represents the Exchange Server 2010 host name.

No proxy

If no proxy is used, please type the following command to restore the default values:

netsh winhttp reset proxy
netsh winhttp reset tracing