Thanks for the reminder to enable TLS. My issue was related to my self-signed SSL certificate and lack of familiarity with how PHP handles SSL contexts. Prior to upgrading to 1.3.6, the Roundcube installation resided on the mail server and accessed the managesieve daemon through localhost:4190 so, obviously, there was no need for SSL. To fix the problem, I ensured that my SSL certs were properly hashed in their directory and set the respective options in config.inc.php as follows:
$config['managesieve_conn_options'] = array(
'ssl' => array(
'verify_peer' => true,
'allow_self_signed' => true,
'capath' => '/etc/ssl/certs',
)
);
Thank you for your assistance and for providing a superlative web-based e-mail package.
--
W.