Exchange Server 2010 like its predecessor Exchange Server 2007 makes heavy use of SSL certificates for various communications protocols. When you install a new Exchange server is comes pre-configured with a self-signed certificate. Before putting a new server into production you should create and assign a new SSL cert for the server.
If you're using an internal DNS namespace that you don't own or is not valid (eg, .local) you may also need to read How to Deal with SSL Requirements for Exchange when Certificate Authorities Won’t Issue You a Certificate
In this example an SSL cert is being configured for the contoso.local organzation.
Generate a New Exchange Server 2010 Certificate
In the Exchange Management Console navigate to Server Configuration. Right-click the server and choose New Exchange Certificate.
Enter a friendly name for the new cert. In this example I have named it “Contoso Exchange Server”.
Although wildcard certificates are supported in Exchange Server 2010 it is recommended to use a SAN (Subject Alternative Name) cert instead.
Next we can configure the names for each of the Exchange 2010 services that are secured with the SSL certificate.
First is the Outlook Web App service. Enter the internal and external names of Outlook Web App. In this example I am using “ex2010.contoso.local” for internal, and “mail.contoso.local” for external.
Next configure the ActiveSync domain name. For ease of administration and configuration I am using the same name as for Outlook Web App.
Next are the Web Services, Outlook Anywhere and Autodiscover names. Once again I am using the same name of “mail.contoso.local”. For Autodiscover the additional names of “autodiscover.contoso.local” and “autodiscover.xyzimports.local” are also configured, for each of the accepted email domains in this example organization.
The Hub Transport server also requires SSL for secure SMTP communications. In this example I am using the name “mail.contoso.local”.
A legacy name for co-existence is required if you are planning to gradually transition services and data from Exchange 2003 to Exchange 2010. Configure legacy names for each of the namespaces in the organization, in this example “legacy.contoso.local” and “legacy.xyzimports.local”.
When all of the services have been configured proceed to the next step of the New Exchange Certificate wizard.
Confirm that all of the required names have been included in the cert request. You can add any additional names at this stage before proceeding.
Next configure the organization and location information for the certificate, and choose a location to generate the request file.
When you have finished filling out the wizard click the New button to generate the cert request file.
Confirm that the request file was successfully generated.
You will notice that the wizard makes a recommendation as to the type of certificate that is required for your Exchange organization. In most cases a “Unified Communications certificate” will be necessary, which is basically another name for a SAN certificate.
Although you can issue the certificate from a private Certificate Authority it is recommended to use a commercial Certificate Authority such as Digicert.
After you have acquired the new certificate return to the Exchange Management Console, navigate to Server Configuration, right-click the server and choose Complete Pending Request.
Browse to the location of the file you downloaded from the CA and complete the wizard. Confirm that the new SSL certificate was imported successfully.
The new certificate now appears in the list of valid certificates for the server.
Assign the New Certificate to Exchange Server 2010
With the valid SSL certificate installed it is now time to assign it to the Exchange Server 2010 services. Right-click the new certificate and choose “Assign Services to Certificate”.
Choose the new Exchange server and click the Next button.
Choose the services to assign to the certificate. In this example the IIS and SMTP services are being assigned.
Complete the wizard to assign the services to the new SSL certificate. You will be prompted to overwrite the existing self-signed certificate, so choose Yes to that prompt.