错误解决：
Exchange 2007 SP1 server将host Outlook 2007 client和OC 2007 client所需要的Exchange Web Services。其中有个叫Autodiscover service是被作为一个虚拟应用程序运行在Exchange 2007 server上的IIS 6.0中。Outlook 2007和Communicator 2007客户端通过连接到这个Autodiscover虚拟应用程序来发现Exchange 2007可用的service URL。这个连接通过443端口并要求128位加密。如果这张应用到Exchange 2007 Server上IIS 6.0 default website的证书没有被安装，就会收到您所描述的错误信息。这个问题应该不会发生在OL 2003/Exchange 2003 或者OL 2003/Exchange 2007的配置组合中。为了解决这个问题，我们需要确认正确的证书已经被安装在Exchange 2007/IIS server上，请执行下面的步骤来检查：
1. Open IIS Manager on the Exchange 2007 server and locate the Default website.
2. Open the properties for the Default website and activate the Directory Security tab
3. Click on View Certificate and make sure that a Web Server certificate is installed on the Default website that meets the requirements listed below.
a. It should have a subject name that is the FQDN of the Exchange 2007 server
b. It should have an Enhanced Key Usage value of Server Authentication OID 1.3.6.1.5.5.7.3.1
c. It should have Certification Path to the Certificate Authority that is hosting the Certificate Authority certificate for the OL 2007 client.
4. If the customer is using a Public CA e. g. Verisign to acquire their certificates then they will need to purchase one for the Exchange 2007 server. If they are using a Windows PKI to manage certificates then find out if they have a domain certificate auto-enrollment policy enabled that supplies the computer (machine template) certificate. If necessary the customer can use the Windows PKI to manually issue a Web Server certificate to the Exchange 2007 server.
5. When Exchange 2007 is installed on a Windows server it will install a self signed certificate that has the subject name of the single label name for the Exchange 2007 server. This certificate is not sufficient for the HTTPS connectivity that is needed for the Windows client connectivity to the Exchange 2007 Webservices.
一般情况，只需重新向企来根CA重新申请一张证书即可