Sending Emails And Showing Progress

I need a way to show the client that the emails are being sent and how many are left. The way I want to do this, is by opening a window which will send the emails and display the status. The problem is how do I pass it the subject, body and so on. I don't want to use a querystring. I thought of doing it like so:

onSubmit = progress() - this will call a js script which will open the progress window
action = (the page that gets all the values from the form and sends the email)

Is there a way to update the popup window from the "action" page? for example: everytime an email is sent... increase a variable and send it to the popup window, and then close it when its done.