nixos/maddy: Add module for maddy

Co-authored-by: Patrick Hilhorst <git@hilhorst.be>

1 files changed, 247 insertions, 0 deletions

diff --git a/nixos/modules/services/mail/maddy.nix b/nixos/modules/services/mail/maddy.nix
new file mode 100644
index 0000000000000..44cfa3c2908d7
--- /dev/null
+++ b/nixos/modules/services/mail/maddy.nix
@@ -0,0 +1,247 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  name = "maddy";
+  cfg = config.services.maddy;
+  defaultConfig = ''
+    tls off
+
+    auth.pass_table local_authdb {
+      table sql_table {
+        driver sqlite3
+        dsn credentials.db
+        table_name passwords
+      }
+    }
+
+    storage.imapsql local_mailboxes {
+      driver sqlite3
+      dsn imapsql.db
+    }
+
+    table.chain local_rewrites {
+      optional_step regexp "(.+)\+(.+)@(.+)" "$1@$3"
+      optional_step static {
+        entry postmaster postmaster@$(primary_domain)
+      }
+      optional_step file /etc/maddy/aliases
+    }
+    msgpipeline local_routing {
+      destination postmaster $(local_domains) {
+        modify {
+          replace_rcpt &local_rewrites
+        }
+        deliver_to &local_mailboxes
+      }
+      default_destination {
+        reject 550 5.1.1 "User doesn't exist"
+      }
+    }
+
+    smtp tcp://0.0.0.0:25 {
+      limits {
+        all rate 20 1s
+        all concurrency 10
+      }
+      dmarc yes
+      check {
+        require_mx_record
+        dkim
+        spf
+      }
+      source $(local_domains) {
+        reject 501 5.1.8 "Use Submission for outgoing SMTP"
+      }
+      default_source {
+        destination postmaster $(local_domains) {
+          deliver_to &local_routing
+        }
+        default_destination {
+          reject 550 5.1.1 "User doesn't exist"
+        }
+      }
+    }
+
+    submission tcp://0.0.0.0:587 {
+      limits {
+        all rate 50 1s
+      }
+      auth &local_authdb
+      source $(local_domains) {
+        check {
+            authorize_sender {
+                prepare_email &local_rewrites
+                user_to_email identity
+            }
+        }
+        destination postmaster $(local_domains) {
+            deliver_to &local_routing
+        }
+        default_destination {
+            modify {
+                dkim $(primary_domain) $(local_domains) default
+            }
+            deliver_to &remote_queue
+        }
+      }
+      default_source {
+        reject 501 5.1.8 "Non-local sender domain"
+      }
+    }
+
+    target.remote outbound_delivery {
+      limits {
+        destination rate 20 1s
+        destination concurrency 10
+      }
+      mx_auth {
+        dane
+        mtasts {
+          cache fs
+          fs_dir mtasts_cache/
+        }
+        local_policy {
+            min_tls_level encrypted
+            min_mx_level none
+        }
+      }
+    }
+
+    target.queue remote_queue {
+      target &outbound_delivery
+      autogenerated_msg_domain $(primary_domain)
+      bounce {
+        destination postmaster $(local_domains) {
+          deliver_to &local_routing
+        }
+        default_destination {
+            reject 550 5.0.0 "Refusing to send DSNs to non-local addresses"
+        }
+      }
+    }
+
+    imap tcp://0.0.0.0:143 {
+      auth &local_authdb
+      storage &local_mailboxes
+    }
+  '';
+
+in {
+  options = {
+    services.maddy = {
+      enable = mkEnableOption "Maddy, a free an open source mail server";
+
+      user = mkOption {
+        default = "maddy";
+        type = with types; uniq string;
+        description = ''
+          Name of the user under which maddy will run. If not specified, a
+          default user will be created.
+        '';
+      };
+      group = mkOption {
+        default = "maddy";
+        type = with types; uniq string;
+        description = ''
+          Name of the group under which maddy will run. If not specified, a
+          default group will be created.
+        '';
+      };
+
+      hostname = mkOption {
+        default = "localhost";
+        type = with types; uniq string;
+        example = ''example.com'';
+        description = ''
+          Hostname to use. It should be FQDN.
+        '';
+      };
+      primaryDomain = mkOption {
+        default = "localhost";
+        type = with types; uniq string;
+        example = ''mail.example.com'';
+        description = ''
+          Primary MX domain to use. It should be FQDN.
+        '';
+      };
+      localDomains = mkOption {
+        type = with types; listOf str;
+        default = ["$(primary_domain)"];
+        example = [
+          "$(primary_domain)"
+          "example.com"
+          "other.example.com"
+        ];
+        description = ''
+          Define list of allowed domains.
+        '';
+      };
+      config = mkOption {
+        type = with types; nullOr lines;
+        default = defaultConfig;
+        description = ''
+          Server configuration.
+        '';
+      };
+
+      openFirewall = mkOption {
+        type = types.bool;
+        default = false;
+        description = ''
+          Open the configured incoming and outgoing mail server ports.
+        '';
+      };
+
+    };
+  };
+
+  config = mkIf cfg.enable {
+
+    systemd = {
+      packages = [ pkgs.maddy ];
+      services.maddy = {
+        serviceConfig = {
+          User = "${cfg.user}";
+          Group = "${cfg.group}";
+        };
+        wantedBy = [ "multi-user.target" ];
+      };
+    };
+
+    environment.etc."maddy/maddy.conf" = {
+      text = ''
+        $(hostname) = ${cfg.hostname}
+        $(primary_domain) = ${cfg.primaryDomain}
+        $(local_domains) = ${toString cfg.localDomains}
+        hostname ${cfg.hostname}
+        ${cfg.config}
+      '';
+    };
+
+    users.users = optionalAttrs (cfg.user == "maddy") {
+      maddy = {
+        description = "Maddy service user";
+        group = cfg.group;
+        home = "/var/lib/maddy";
+        createHome = true;
+        isSystemUser = true;
+      };
+    };
+
+    users.groups = mkIf (cfg.group == "maddy") {
+      maddy = pkgs.lib.mkForce {
+        name = cfg.group;
+      };
+    };
+
+    networking.firewall = mkIf cfg.openFirewall {
+      allowedTCPPorts = [ 25 143 587 ];
+    };
+
+    environment.systemPackages = [
+      pkgs.maddy
+    ];
+  };
+}