KO Binding with mailto

HTML

Option 1: 
<a data-bind="attr:{href:'mailto:' + Email()},text:Email"></a>

<br/>

Option 2: 
<a data-bind="attr:{href:EmailLink},text:Email"></a>

JavaScript

var myViewModel = function() {
    var self = this;
    self.Email = ko.observable("[email protected]");
    self.EmailLink = ko.computed(function() {
        return "mailto:" + self.Email();
    });
}

ko.applyBindings(new myViewModel);
window.open('mailto:[email protected]?subject=Feedback%20zu%20einem%20KVP2GO%20Modul&amp;body=Hallo%20KVP-Team,%0D%0A%0D%0Aich%20möchte%20ein%20Feedback%20abgeben.');