[devote]

<form id="postform" method="post" action="./posting.php?mode=post&f=1" enctype="multipart/form-data" onsubmit="return preSubmit();">
...
<div id="message-box">
<textarea name="message" id="message" rows="15" cols="76" tabindex="4" class="inputbox"></textarea>
</div>
...
<input type="submit" accesskey="s" tabindex="6" name="post" value="Отправить" class="button1 default-submit-action" />
</form>

<script type="text/javascript">
    function preSubmit() {
        if ( !confirm( "Отправить форму?" ) ) {
            return false;
        }
    }
</script>