showComposeNewEmailAsync "Not implemented" from Cordova plugin call.

[Paul Hemans]

On a Windows 8.1 Phone device a Cordova app plugin is accessing showComposeNewEmailAsync here is the code;

exports.open = function (success, error, args) {
var props = args[0],
email = exports.getDraftWithProperties(props);

Windows.ApplicationModel.Email.EmailManager
.showComposeNewEmailAsync(email)
.then(function () {
success();
},
function (err) {
error(err);
})
.done(success,
function (err) {
error(err);
});
};

I get an error of "Not Implemented", it would seem from other posts that this method is available on this platform. What am I missing?