<script type="text/javascript">
     $(function() {
			$('#check').click(function() {
                                var mail = $('#mail').val();
				$.ajax({
					type: "POST",
					url: "check.php",
					data: "mail="+mail,
					success: function(html){
						$("#container").html(html);
					}
				});
            });
	});
</script>
<input type="text" name="mail" id="mail"/>
<input type="submit" value="check" id="check"/>
<div id="container"></div>