Update: I have found a fix. I changed $rcmail_config['imap_auth_type'] = null; to $rcmail_config['imap_auth_type'] = 'CRAM-MD5';
in /etc/roundcube/main.inc.php, now it works. -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org