[Dovecot] SSL and STARTTLS

I wanted to enable SSL on some alternate ports so that a limited number of people could try SSL access. But doing so enabled STARTTLS in IMAP, so that all IMAP users got surprised (at least those whose clients attempted to use it automatically).

e.g.:

# IP or host address where to listen in for SSL connections. Defaults
# to above non-SSL equilevants if not specified.
imaps_listen = *:xxxx
pop3s_listen = *:yyyy

# Disable SSL/TLS support.

ssl_disable = no

Is there a way to enable imaps/pop3s without enabling STARTTLS?

(If so it's probably blindingly obvious and I am missing it..)

Yours, mm