Event 12014 - Microsoft Exchange could not find a certificate...
Microsoft Exchange 2007 regularly logs following errors in Windows Application Logs:
Event ID: 12014
Microsoft Exchange could not find a certificate that contains the domain name <server-name.domain.local> in the personal store on the local computer. Therefore, it is unable to support the STARTTLS SMTP verb for the connector Default Send Connector with a FQDN parameter of <server-name.domain.local>. If the connector's FQDN is not specified, the computer's FQDN is used. Verify the connector configuration and the installed certificates to make sure that there is a certificate with a domain name for that FQDN. If this certificate exists, run Enable-ExchangeCertificate -Services SMTP to make sure that the Microsoft Exchange Transport service has access to the certificate key.