I have evaluated roundCubeMail latest alpha release back in early November and I liked it. I did have some trouble using it on IMAP server from OpenVMS boxes (hangs and timeout during login), but after few cvs updates, it solved the problem.
Around in December, maybe before, some of cvs snapshots now have giving me some problems, the Inbox pane is displaying new messages incorrectly. Even with the latest cvs snapshot, the problems still exist. I have attached two jpeg files. The 1st jpeg file shows Inbox pane with new messages but with blank subject, sender, and date. If you double click on it, load snippet appears and will hang if left to long. I can move new messages the different folder and able to read them as if they are old messages. If I move one new message back to Inbox (see 2nd jpeg file) it will appear as two messages, old message with blank header, and new message with correct header. Again, I can read the old message but not the new one.
Roundcubemail box: Gentoo with Apache2 server
IMAP box: OpenVMS with PDMF IMAP server
RoundCubeMail works great on MS Exchange IMAP server with no problems. But we have over 20,000 e-mail users on OpenVMS clusters. We need fast, but simple and ease of use mail web-interface with all the standard features; RoundcubeMail shows promises. Squirrelmail chokes and our current mail web-interface Webmail (commercial) lack features and is too slow. Hordes Impmail does PDMF IMAP very well, but lacks features plus installation and configuration are difficult and pain in the ass.