¿Doy you know RoundCube [1]?It's a young project, and it lacks some common features (as a HTML composer, which is currently in experimental/beta stage) but it seems to go in right direction. Moreover, the visual environment is so pleasant.
[1] http://roundcube.net/ _______________________________________________ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
