rules: {
            EmailAddress: {
                required: true
            }
        },
        messages: {
            EmailAddress: {
                required: "<br/> Please enter the Email address"
            }
        }
    });

public class MyModel
 {
     [Required(ErrorMessage = "Please enter the Email address")]
     public string Email { get; set; }
 }

if ($("#RegisterForm").valid()) {
    $("#RegisterForm").submit();
}