It means that you have allowplaintext:no set in imapd.conf, which disables and plaintext authentication mechanism (either protocol specific or PLAIN/LOGIN) unless protected by an external layer (eg. SSL/TLS).
Not mine, just found it here.
Hi i just have here similar problem and courier-imap is accepting plain text auth..
in normal work...5 minutes working normaly and then (logged in) i get connect timeout to browser...
in logs is shown that roundcube cannot auth to imap server, but imap server is working and didnt get request from roundcube to auth...
BTW why is roundcube send login/logout 2-4times in every action i do in browser ? it cannot use 1 imap connection to logged user to every action ?
any suggestion ?
info: apache 2.2.9.5, php 5.2, courier-imapd 4.4.1, os FreeBSD 7.0