simple form/variable question

this is a simple question, hopefully with an extremely easy answer which eludes me for reasons unknown
i have a site with a simple form
the form page is called [i]form.php[/i] and the submit page is called [i]submit.php[/i]. submit.php mails the contents of the form.

on form.php there are a few form elements which are check boxes.

[code]<input type=’checkbox’ name=’newsletter’ value=’Yes’ checked>[/code]

If the box is unchecked, and you press the submit button on form.php, the next page will have [b]Notice: Undefined variable: newsletter in pathtothefilecalledsubmit.php on line 15[/b]. [line 15 is a line which includes the contents of the form, in a mail() function]
This variable problem only exists if the box is left unticked. Is there a way to get the form to pass a value for $newsletter through the browser, even if the box isn’t ticked?

many thanks.

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