if ( ! apply_filters( 'enable_post_by_email_configuration', true ) )
wp_die( __( 'This action has been disabled by the administrator.' ), 403 );
+$mailserver_url = get_option( 'mailserver_url' );
+
+if ( 'mail.example.com' === $mailserver_url || empty( $mailserver_url ) ) {
+ wp_die( __( 'This action has been disabled by the administrator.' ), 403 );
+}
+
/**
* Fires to allow a plugin to do a complete takeover of Post by Email.
*