This simple snippet validates the email field to have email of specific domain

validate-domain.js

jQuery.validator.addMethod("domain_email", function(value, element, param) {                
    if (/^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/.test(value)) {
        if (value.indexOf(param, value.length - param.length) !== -1) {
            return true;
        } else {
            return false;
        }
    } else {
        return false;
    }
}, function(param) {
    return "Email must end with the domain '" + param +"'"
});