{ pkgs, lib, config, ... }:
let inherit (lib) types;
    inherit (pkgs.lib) unlinesAttrs unwords;
    inherit (config) networking;
    inherit (config.services) postfix;
in
{
options.services.postfix = {
  aliases = lib.mkOption {
    type = with types; attrsOf (listOf str);
    default = {};
    example = { "root@${networking.domain}" = [
                  "user1@${networking.domain}"
                  "user2@${networking.domain}"
                ];
                "@example.coop" = ["user1@${networking.domain}"];
              };
  };
};
config = lib.mkIf postfix.enable {
  services.postfix = {
    mapFiles."virtual_alias_maps" = pkgs.writeText "virtual_alias_maps"
      (unlinesAttrs
       (from: to: "${from} ${unwords to}")
       postfix.aliases);
    config = {
      virtual_alias_maps = [
        "hash:/etc/postfix/virtual_alias_maps"
      ];
    };
  };
};
}