self signed certs and dovecot imaps : howto? tlsv1 alert unknown ca

[hanasaki at gmail.com]

How do you setup dovecot to use a self signed cert?  One server will be 
connected to the internet.  One will be totally internal and have no 
runtime access to the internet.  Getting the below error msg.  Also, I 
think I have a TLS 1.0 and need a 1.2 cert?...

Thank you.

Jul 28 20:09:27 host dovecot: imap-login:: user=<>, rip=10...., 
lip=10...., TLS: SSL_read() failed: error:14094418:SSL 
routines:ssl3_read_bytes:tlsv1 alert unknown ca: SSL alert number 48, 
session=<kK2aELspLpkKAQF5>