How to make sync_client invoke STARTTLS for replication

[Rich Wales]

I'm running Cyrus 2.3.16 (with replication) between two Ubuntu servers.

What do I have to do to make the "sync_client" application invoke STARTTLS
when it connects to "sync_server" on the other host?

I can invoke TLS when I use the "synctest" program, but I can't seem to
figure out how to force "sync_client" to use TLS when actually replicating.

The reason I'm assuming TLS is not happening is that when /var/log/syslog
records the "User logged in" events associated with replication, TLS is
not mentioned as part of the authentication mechanism in use.

Right now, the lack of TLS is not a major issue because one of the servers
is connected to my LAN via a VPN link (so it's encrypted).  But I still
want to know what I'm supposed to do in order for a TLS layer to happen.

Rich Wales
richw at richw.org