I have a Zimbra server that has a Barracuda doing both inbound and outbound relay. I would like the configuration to attempt a tls connection both ways, but not force to tls. I believe I have to configure this way because I have some clients connecting directly to the Zimbra server that are not configured for tls yet. I assume I need to make some changes in the postfix config but I am nervouse as I do not want to break the non tls clients connection.

Thank you for any assistance!