Regarding Exchange 2013 Public Certificates I have found that the UCC certificate for 3years is almost the price of the Exchange application.
Accessing the Exchange Server Remotely (via OWA or POP/IMAP) I receive a warning that the certificate is un-trusted. Therefore after buying a Public Certificate this warning will disappear.
But what are the other benefits that I will have using a Public Certificate for Exchange (since it seems overpriced)??