Code:
Jan 10 23:10:38 myhostname postfix/smtpd[13079]: connect from myisp.domain.com[myipaddress]
Jan 10 23:10:39 myhostname postfix/smtpd[13079]: warning: TLS library problem: 13079:error:14094412:SSL routines:SSL3_READ_BYTES:sslv3 alert bad certificate:s3_pkt.c:1256:SSL alert number 42:
Jan 10 23:10:39 myhostname postfix/smtpd[13079]: lost connection after STARTTLS from myisp.domain.com[myipaddress]
Jan 10 23:10:39 myhostname postfix/smtpd[13079]: disconnect from myisp.domain.com[myipaddress]
which basically makes secure smtp impossible.

Then I read in http://linuxlasse.net/linux/howtos/Postfix_with_TLS:

Code:
If I copy the CA certificate to the store of tls files it is working as inteded. I am not sure why, but it is working.
The location could differ from your setup.

#cp ca.crt /etc/postfix/tls

And restart postfix

#/etc/init.d/postfix restart

Note if you enable TLS, and are sending through and relay server which does not support TLS, outbound connections will ofcourse not be encryptet.
Where can I find the certificates to try this?