I need to validate the duplicate of FirstName, LastName and Email Address combination using remote validation in my ASP.NET MVC 4 (C#) application. The Remote Validation accepts only one AdditionalFields, which is as below:
 [Remote("IsUserNameAvailable", "User", AdditionalFields="LastName" )]
 public string FirstName{ get; set; }
 public string LastName{ get; set; }
 public string EmailAddress{ get; set; }
How can i add the EmailAddress for the combination?