WPCF7 - Send copy to sender with checkbox (Kudos to http://www.motomax.de/wordpress/contact-form-7-send-copy-to-sender-with-checkbox-in-3-9-update/ and https://gist.github.com/mathiasmadsen/afd06d5380f74c080fb104ac5fd6eaea)

WPCF7 - Send copy to sender with checkbox

1. Open the CF7 contact form which you want to edit in wordpress Admin area. You set up the [checkbox] snippet which produces the checkbox in the contact form on your website:
[checkbox contact_sendmail "Send me a copy of this message"]

2. Activate Mail(2)


3. Add to functions.php
function check_mail_send_contactform($cf7)
{
    $submission = WPCF7_Submission::get_instance();
    if ( $submission )
    {
        $posted_data = $submission->get_posted_data();
    }
    $mail = $cf7->prop( 'mail' );

    if(!empty($posted_data['contact_sendmail'][0]))
    {
        $mail2 = $cf7->prop( 'mail_2' );
        $mail2['recipient'] = $posted_data['your-email'];
        $cf7->set_properties( array( 'mail_2' => $mail2 ) );
    }
    else {
        $cf7->set_properties( array( 'mail_2' => array() ));
    }
    return $cf7;
}

add_action('wpcf7_before_send_mail','check_mail_send_contactform');