anchor.diff:        serviceConfig.ExecStart = "${cfg.package}/sbin/smtpd -d -f ${conf} ${args}";
         environment.OPENSMTPD_PROC_PATH = "${procEnv}/libexec/opensmtpd";
       };
  -
  -    environment.systemPackages = mkIf cfg.addSendmailToSystemPath [ sendmail ];
     };
   }
  
positive.code:         description = "The OpenSMTPD package to use.";
        };
  
        addSendmailToSystemPath = mkOption {
          type = types.bool;
          default = true;
          description = ''
            Whether to add OpenSMTPD's sendmail binary to the
            system path or not.
          '';
        };
  
        extraServerArgs = mkOption {
  
negative.code: 
    ###### implementation
  
    config = mkIf cfg.enable rec {
      users.groups = {
        smtpd.gid = config.ids.gids.smtpd;
        smtpq.gid = config.ids.gids.smtpq;
  