I think Roundcubemail really promise but:
There are still some things that i consider to be bugs:
to read the new e-mails i have to first mark them as read with the specification that sometimes it works but only for the first time after authentification and only for the first e-mail i open.
I would also want like the posibility to delete attachements if added by mistache from the e-mail being composed and not leavinng the e-mail i compose and having only the oportunity to start a new message if i added some attachements that i do not want after all to send...