functions.php

// хук перед отправкой CF7
function my_function( $contact_form ) {
    $title = $contact_form->title();
    $submission = WPCF7_Submission::get_instance();

    if ( $submission ) {
        $posted_data = $submission->get_posted_data();
    }

    if ( 'Form Title' == $title ) { //нужная ли форма
        // Form fields
        $name = $posted_data['name'];
        $email = $posted_data['coupon-email'];

        //код


        return true;
    }
}

add_action( 'wpcf7_mail_sent', 'my_function', 10 , 1 );