Custom jquery validate
jQuery.validator.addMethod("checkForExistEmail", function (value, element, param) { var ajaxFunc = $.ajax({ async: false, data: { emailValidate: value }, type: 'POST', url: '/url?c=checkEmailExist', dataType: 'json' }); if (ajaxFunc.responseText == 1) return true; else return false; }, "This email exist. Please choose another email address"); jQuery.validator.addMethod("checkForEmail", function (value, element, param) { var re = /^(([^<>()[\]\\.,;:\s@\"]+(\.[^<>()[\]\\.,;:\s@\"]+)*)|(\".+\"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/; return re.test(value); }, "Please enter a valid email address.");