anchor.diff:  
     ###### implementation
   
  -  config = mkIf config.services.opensmtpd.enable {
  +  config = mkIf cfg.enable {
       users.extraGroups = {
         smtpd.gid = config.ids.gids.smtpd;
         smtpq.gid = config.ids.gids.smtpq;
  
positive.code:   cfg = config.services.opensmtpd;
    conf = writeText "smtpd.conf" cfg.serverConfiguration;
    args = concatStringsSep " " cfg.extraServerArgs;
  
  in {
  
  
negative.code:       environment.OPENSMTPD_PROC_PATH = "${procEnv}/libexec/opensmtpd";
      };
  
      environment.systemPackages = mkIf cfg.addSendmailToSystemPath [ sendmail ];
    };
  }
  