override jquery validate plugin email address validation

I wouldn’t do this but for the sake of an answer you need to add your own custom validation.

//custom validation rule
$.validator.addMethod("customemail", 
    function(value, element) {
        return /^\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*$/.test(value);
    }, 
    "Sorry, I've enabled very strict email validation"
);

Then to your rules add:

rules: {
                    email: {
                        required:  {
                                depends:function(){
                                    $(this).val($.trim($(this).val()));
                                    return true;
                                }   
                            },
                        customemail: true
                    },