Hi,
first of all, congratulations for your project! very good..
But i've some problem with configuration, when i try to make a sub-folder of inbox folder i get error, i think that is a problem of configuration, infact my hosting provided to me an installation of roundcube where subfolder of Inbox are admitted.. In my personal configuration of Roundcube instead i can't create a sub-folder of Inbox..
My configuration
best regards,
nicola.