Event ID 12014 may appear in the Application event log of CAS/HUB Transport/Edge server:

         “Microsoft Exchange couldn’t find a certificate that contains the domain name mail.domainname.com
         in the personal store on the local computer. Therefore, it is unable to offer the STARTTLS SMTP
         verb for any connector with a FQDN parameter of mail.domainname.com.
         Verify the connector configuration and the installed certificates to make sure that there is
         a certificate with a domain name for every connector FQDN.”

This means that you are missing a cert for a SMTP connector

Here is the solution:

New-ExchangeCertificate -Domain Name “mail.yourdomain.com”, “computername” -Services “SMTP”

Enable-ExchangeCertificate “thumbprint recieved above” -Services “SMTP”

Links

http://www.webservertalk.com/message2184491.html

http://support.microsoft.com/kb/555855