As of 11:07 Paris time, my e-mails via Roundcube are still there. However, over the past several hours access to the website was inconsistent (at one point earlier this morning, I could not even login). So, perhaps you will find the emails if you logout, then try again in an hour or two.
I was just able to access both IMAP and Roundcube (webmail.eu.com), and my archive folder with years of folder does not exist at the moment.
I see only 2 emails in the inbox, nothing else. There are no other mailbox folders besides from inbox either. All gone.