I want redirect to another domain users of Internet Explorer but redirect always.

My settings

server {
server_name prueba.midominio.es;
index index.html

access_log /var/log/nginx/prueba-access;
error_log /var/log/nginx/prueba-error;

root /var/www/localhost/htdocs/indes;

if ($http_user_agent ~ MSIE ) {
rewrite ^ http://prueba2.midominio.com$request_uri? permanent;
}
}