CodeIgniter - check username exists, JS validation plugin

checkUsername.js

rules: {
	email1: {
		required: true,
		email: true,
		remote: {
			url: "/registration/register_email_exists",
			type: "post",
			data: {
				email: function(){ return $("#email").val(); }
			}
		}
	},
	email2: { equalTo: "#email" }
},
messages: {
	email1: {
		required: 'Email address is required',
		email: 'Please enter a valid email address',
		remote: 'Email already used. Log in to your existing account.'
	}
}