I have problems when i'm using smartphone and roundcube.
I can't open an emails.
True. The standard roundcube skins are not designed for a touch interface. There are a few third-party add-on skins that are said to work on mobile devices. If you run your own roundcube installation, look into adding a mobile-friendly skin. If you don't run your own system, contact your email provider to ask for mobile device support.