Certificate Expiration Alerting
Microsoft Lync Server and Microsoft Exchange Server utilize certificates to manage encryption and authentication. When certificates expire unexpectedly, network administrators are under pressure to resolve the problem quickly. Fortunately, most trusted Certificate Providers inform customers by email before certificates expire. But what happens when certificates are issued by an internal Microsoft Windows Certification Authority? If customers do not have a monitoring solution, such as Microsoft System Center Operations Manager, to provide status updates on certificate expirations, it is a real challenge to keep track of scheduled certificate expirations. The Certificate Expiration Alerter is a free tool that helps prevent unplanned certificate expirations.
Read more at source: http://blogs.technet.com/b/nexthop/archive/2011/11/18/certificate-expiration-alerting.aspx