How to retrieve all rows from Data Extension using WSProxy

Question

I need to retrieve all rows from a data extension to create a validateEmail API call. There are almost 400 000 users in the data extension, so I need to use WSProxy, because it allows to retrieve more than 2500 rows.

It doesn't work when I try to retrieve data extension.

<script runat='server'>
Platform.Load("core","1.1.1");
var config = {
           name: "VegetarianDE" (this is the name of my data extension within contact builder)
           cols: ["SubscriberKey, "EmailAddress"] (I have 2 fields in this data extension)
}
var prox = new Script.Util.WSProxy();
var data = prox.retrieve("DataExtensionObject[" + config.name + "]", config.cols);

Write("first row in retrieved data is " + data.results[0].EmailAddress) 

</script>

I receive 'first row in retrieved data is undefined'.