anchor.diff:          description = "
             Entries for the virtual alias map.
           ";
  +      };
  +
  +      extraMasterConf = mkOption {
  +        default = "";
  +        example = "submission inet n - n - - smtpd";
  +        description = "Extra lines to append to the generated master.cf file.";
         };
   
       };
  
positive.code:       extraConfig = mkOption {
          default = "";
          description = "
            Extra configuration, will be added verbatim to the configuration file.
          ";
        };
  
  
negative.code:             ${pkgs.coreutils}/bin/chown root:root /var/spool/mail
              ${pkgs.coreutils}/bin/chmod a+rwxt /var/spool/mail
  
              ln -sf "${pkgs.postfix}/share/postfix/conf/"* /var/postfix/conf
  
              ln -sf ${aliasesFile} /var/postfix/conf/aliases
              ln -sf ${virtualFile} /var/postfix/conf/virtual
              ln -sf ${mainCfFile} /var/postfix/conf/main.cf
              ln -sf ${masterCfFile} /var/postfix/conf/master.cf
  
              ${pkgs.postfix}/sbin/postalias -c /var/postfix/conf /var/postfix/conf/aliases
              ${pkgs.postfix}/sbin/postmap -c /var/postfix/conf /var/postfix/conf/virtual
  
              exec ${pkgs.postfix}/sbin/postfix -c /var/postfix/conf start
            '';
  
          preStop = ''
              exec ${pkgs.postfix}/sbin/postfix -c /var/postfix/conf stop
  