the javascript Date().toString() method doesn't create a valid RFC822 'date'. you can see that it's wrong by looking in eg gmail - view the actual message (instead of just the thread in your inbox) and you'll see the time is wrong by several hours (depending on your timezone).
there's an example of creating a valid RFC822 date in javascript here:
http://www.sanctumvoid.net/jsexamples/rfc822datetime/rfc822datetime.html
it would be nice to have a method to do this in the node-smtp library..