JMX get MBeanAttributeInfo of specific attribute directly
//server is an MBeanServer
MBeanAttributeInfo[] infos = server.getMBeanInfo(new ObjectName("jboss:service=Mail"));
for(MBeanAttributeInfo info : infos) {
    if(info.getName().equals("State")) {
        if(info.isWritable()) {
            //do something
        }
        break;
    }
}