Postfix: Disable SSLv2 and SSLv3 for mandatory TLS connections

Postfix: Disable SSLv2 and SSLv3 for 'mandatory SSL' mode connections to completely mitigate the POODLE issue.

roles/mailserver/templates/etc_postfix_main.cf.j2

 unverified_sender_reject_code = 554
 
 # TLS parameters
+smtpd_tls_mandatory_protocols=!SSLv2,!SSLv3
+smtp_tls_mandatory_protocols=!SSLv2,!SSLv3
 smtpd_tls_cert_file=/etc/ssl/certs/wildcard_combined.pem
 smtpd_tls_key_file=/etc/ssl/private/wildcard_private.key
 smtpd_use_tls=yes