roundcube user. Here is an example of that procedure:
# mysql
-> CREATE DATABASE roundcubemail;
+> CREATE DATABASE roundcubemail /*!40101 CHARACTER SET utf8 COLLATE utf8_general_ci */;
> GRANT ALL PRIVILEGES ON roundcubemail.* TO roundcube@localhost
IDENTIFIED BY 'password';
> quit
which ever is the database superuser):
$ createuser roundcube
-$ createdb -O roundcube roundcubemail
+$ createdb -O roundcube -E UNICODE roundcubemail
$ psql roundcubemail
roundcubemail =# ALTER USER roundcube WITH PASSWORD 'the_new_password';