Date format when email form

Here is the script for the email button:

var myDoc = event.target;
var address = "xxx@xxxcom";
var sub = "MANAGER FORM ";
var msgBody = "See my Form attached.\n\nThank You!";
var Sender = ( form1.Page1.Last_Name.rawValue+" "+ form1.Page1.First_Name.rawValue+" "+ form1.Page1.Effective_Date.rawValue);

myDoc.mailDoc({ bUI: false,
cTo: address,
cSubject: sub + Sender,
cMsg: msgBody,
cSubmitAs: "PDF"});

For the Effective_date field the date pattern is :date{MMMM D, YYYY} but when I press the email button I am getting the date as YYYY-MM-DD into subject line(Microsoft Outlook)!

How I can get date patern as date{MMMM D, YYYY}?

Thanks