{
  lib,
  config,
  ...
}: let
  cfg = config.customOps;
in {
  options = with lib; {
    customOps = mkOption {
      description = "custom options";
      type = types.submodule {
        options = {
          owner = mkOption {
            type = types.submodule {
              options = {
                username = mkOption {
                  type = types.str;
                  default = null;
                };
                pubkey = mkOption {
                  type = types.str;
                  default = null;
                };
              };
            };
            description = "machine owner";
          };
          domain = mkOption {
            type = types.submodule {
              options = {
                name = mkOption {
                  type = types.str;
                  default = null;
                };
                tld = mkOption {
                  type = types.str;
                  default = null;
                };
                fqdn = mkOption {
                  type = types.str;
                  default = "${cfg.domain.name}.${cfg.domain.tld}";
                };
              };
            };
            description = "machine domain name";
          };
          mailAccounts = mkOption {
            type = types.attrsOf (types.submodule {
              options = {
                passwdFile = mkOption {
                  type = types.str;
                  default = null;
                };
                aliases = mkOption {
                  type = types.listOf types.str;
                  default = [];
                };
                aliasesRegex = mkOption {
                  type = types.listOf types.str;
                  default = [];
                };
                catchAll = mkOption {
                  type = types.listOf types.str;
                  default = [];
                };
                sendOnly = mkOption {
                  type = types.bool;
                  default = false;
                };
              };
            });
            description = "accounts for the mail server";
          };
        };
      };
    };
  };
}