So that defiantly looks like an SSL error, you may want to try setting the following settings.
// IMAP socket context options
// See http://php.net/manual/en/context.ssl.php
// The example below enables server certificate validation
//$config['imap_conn_options'] = array(
// 'ssl' => array(
// 'verify_peer' => true,
// 'verify_depth' => 3,
// 'cafile' => '/etc/openssl/certs/ca.crt',
// ),
// );
$config['imap_conn_options'] = null;
// SMTP socket context options
// See http://php.net/manual/en/context.ssl.php
// The example below enables server certificate validation, and
// requires 'smtp_timeout' to be non zero.
// $config['smtp_conn_options'] = array(
// 'ssl' => array(
// 'verify_peer' => true,
// 'verify_depth' => 3,
// 'cafile' => '/etc/openssl/certs/ca.crt',
// ),
// );
$config['smtp_conn_options'] = null;