Javascript in message.read

In the delicious sample app, it says that you can inject JavaScript into an
email before it is displayed. Are there any other guidelines about this? Will
any JavaScript in the email be executed at display time?

Thanks!

~Josh



From
http://developer.yahoo.com/mailapplication.../delicious.html

The Delicious Sample App:

Uses a message.read event listener so that it's invoked whenever the user opens
email with a particular subject line.
Modifies the way such email is initially rendered.
Injects javascript into such email to make the email more interactive.
Calls an external web service to expand content available within the email.
Requires the new Yahoo! Mail Beta (unlike all the other samples).