Could I just poke you devs to please include STARTTLS support sooner rather than later? I just lost a few hours writing a patch to add this (I don't know PHP) and later discovered that someone had already done the same:
http://trac.roundcube.net/ticket/1485284
The implementation isn't that complex and I've found more than a few messages online involving people trying to get roundcube to use TLS. I believe STARTTLS is considered the standard way to do both encrypted IMAP and SMTP (STARTTLS in SMTP is already supported) and it's quite irritating to have to open up an extra port for IMAP over SSL.
Regards,
Francis
List info: http://lists.roundcube.net/dev/