codice:
$(".submit").click(function(e){
    if(validaEmail()){
    	$.ajax({
    	      url: 'AJAXvalidate.php',
    	      type: "POST",
    	      data: "email="+email.val(),
    	      success: function(data) {
    	        //if it's NOT valid
    	        if(data=="error"){
    	          email.addClass("error");
    	          emailError.html("E-mail già presente");
    	    			emailError.addClass("error");
    	    			
    	    			
    	        }
    	        else{
					form.submit();
        	        }
    	    });
}
	});