First, if you're using up-imapproxy with SSL, you have Ken Murchison
to thank for that.  He added this feature.

up-imapproxy only supports TLS between the proxy server and the real
IMAP server.  It does not support TLS between a client (usually webmail)
and the proxy server.  The idea here is that you can run the imap proxy on
the same machine as your webserver.  If you're using TLS to your webserver,
the webserver can then send plaintext auth to the proxy without the password
ever crossing the network, then the proxy can use TLS to the IMAP server.

The proxy will only use TLS if the real imap server forces it to do so by
advertising LOGINDISABLED in the capability string.

imapproxy does not support the deprecated notion of imaps using port 993.
It only supports the use of the STARTTLS command to initiate SSL/TLS from
within a regular imap connection.

There are four configuration file options that you'll have to set in order
for SSL to work.  They are tls_ca_file, tls_ca_path, tls_cert_file and
tls_key_file.

I haven't had time to write my own ssl tuturial (and I might never) but you
can find a wealth of information here:

http://www.sendmail.org/~ca/email/starttls.html

If anyone wants to contribute to this project by submitting some good
documentation about configuring up-imapproxy with TLS, it would be appreciated.