public class RegisterModel
{
    [Required(ErrorMessage = "Phone number is required")]
    [DataType(DataType.PhoneNumber)]
    [Display(Name = "Phone number")]
    public string PhoneNumber { get; set; }

    [Required(ErrorMessage = "E-mail address is required")]
    [DataType(DataType.EmailAddress, ErrorMessage = "Please enter a valid date (ex: 2/14/2011)")]
    [Display(Name = "E-mail address")]
    public string Email { get; set; }
}

<script src="@Url.Content("~/Scripts/jquery.unobtrusive-ajax.min.js")" type="text/javascript"></script>

<appSettings>
    <add key="ClientValidationEnabled" value="true"/>
    <add key="UnobtrusiveJavaScriptEnabled" value="true"/>
</appSettings>

[HttpPost]
        public ActionResult SaveRegisterDetails(Register registerDetails)
        {
            if (ModelState.IsValid)
                return View();
            else
                return View("Index", registerDetails);
        }

[Required]
[DataType(DataType.EmailAddress)]
[EmailAddress(ErrorMessageResourceName = "MustBeEmail", ErrorMessageResourceType = typeof(Resources))]
public string Email { get; set; }

<appSettings>
    <add key="ClientValidationEnabled" value="true"/>
    <add key="UnobtrusiveJavaScriptEnabled" value="true"/>
</appSettings>