Hi Chris!
Yes, I do have access via phpmyadmin. But unfortunately I have to check imap accounts hosted on 4 different servers. That's why I would appreciate it so much, if roundcube or better eyemail supported IMAP at all with multiple accounts.
Recently I also installed iloha mail, which works fine, but doesn't support multiple accounts either.
Thanks a lot for your advise!

At the moment I am not actively searching for a solution, but I will keep an eye on further development here and among other easy-to-install webmail-skripts.
Bye!