此表单收到了大量垃圾邮件，我想了解一些如何防止垃圾邮件的建议。

我不应该使用任何插件或验证码。

 function innerpages_form($atts, $content = null)
{
    session_start();
    // Attributes
    extract(
        shortcode_atts(
            array(
                \'title\' => \'\',
            ),
            $atts
        )
    );
    // Code
    //global $wp_session;

    return \' <div class="sell-fast-form">


    <form action="/sell-now/" method="post" id="myForm">

    <h2 style="color:#f15a29">Need To Sell Your House Fast?</h2><br>

      <h2>Property Address</h2>
                <input type="text" class="Property_Address" name="Property_Address" id="addr" placeholder="Property Address" value="" required >

                <h2>Phone</h2>
                <input type="text" class="Phone" name="Phone" placeholder="Phone" id="Phone" pattern="^[(]{0,1}[0-9]{3}[)]{0,1}[-\\s\\.]{0,1}[0-9]{3}[-\\s\\.]{0,1}[0-9]{4}$" required title="xxx-xxx-xxxx" >
                <h2>Email</h2>
                <input type="Email"  class="Email" name="Email"  placeholder="Email" id="Email" value="" required >
                <input style="display:none;" type="text" name="robots" value="" />
                <input type="submit" class="click_here" onsubmit="return myFunction();" value="&nbsp; &nbsp; &nbsp; &nbsp; GET MY FAIR CASH OFFER &nbsp; &gt;&gt;&gt;"/>





  <script>
        function myFunction() {
            document.getElementById("myForm").submit();
            return false;
        }
        </script>
</form>

        </div>

      \';
}
add_shortcode(\'innerpages_form\', \'innerpages_form\');