[RCU] Does roundcube support STARTTLS on port 587 for sending mail?

I attempted to set this by changing

// SMTP port (default is 25; 465 for SSL) $rcmail_config['smtp_port'] = 587;

// SMTP username (if required) if you use %u as the username Roundcube // will use the current username for login $rcmail_config['smtp_user'] = '%u';

// SMTP password (if required) if you use %p as the password Roundcube // will use the current user's password for login $rcmail_config['smtp_pass'] = '%p';

but I got 250 errors in roundcube (and nothing but a connect followed by a quick disconnect in the MTA log)... so I'm guessing it doesn't? That or I missed something...