Add mail options

pkgs/pretix/module.nix

@@ -30,7 +30,7 @@ let
     ];
   };
   staticRoot = pkgs.pretix-static;
-  environmentFile = pkgs.runCommand "pretix-environ" runCommandArgs ''
+  environmentFile = pkgs.runCommand "pretix-environ" runCommandArgs (''
     cat > $out <<EOF
     DATA_DIR = /var/pretix
     DJANGO_SETTINGS_MODULE=pretix_wrapper.settings
@@ -50,9 +50,18 @@ let
     PRETIX_REDIS_LOCATION=redis://127.0.0.1:${toString redisPort}/0
     PRETIX_REDIS_SESSIONS=true
     PRETIX_STATIC_ROOT=${staticRoot}
+  '' + (
+    if cfg.mail.enable then
+      ''
+        PRETIX_MAIL_FROM=${toString cfg.mail.from}
+        PRETIX_MAIL_HOST="${cfg.mail.host}"
+        PRETIX_MAIL_PORT=${toString cfg.mail.port}
+      '' else ""
+  ) +
+  ''
     PYTHONPATH=$PYTHONPATH
     EOF
-  '';
+  '');
   mkTimer = { description, unit, onCalendar }: {
     inherit description;
     requires = [ "pretix-migrate.service" ];
@@ -97,6 +106,30 @@ in
       type = types.path;
       description = "Path to the sops secrets file which stores pretix.cfg settings.";
     };
+    mail = {
+      enable = mkEnableOption "Enables or disables emailing.";
+      from = mkOption {
+        type = types.str;
+        description = "The email address to set as From header in outgoing emails by the system.";
+      };
+      host = mkOption {
+        type = types.str;
+        description = "The SMTP Host to connect to.";
+        default = "localhost";
+      };
+      port = mkOption {
+        type = types.port;
+        description = "The SMTP Port to connect to.";
+        default = 25;
+      };
+      admins = mkOption {
+        type = listOf str;
+        description = ''
+          Comma-separated list of email addresses that should receive a report about every error code 500 thrown by pretix.
+        '';
+        default = [ ];
+      };
+    };
     banktool = {
       enable = mkEnableOption "Enable tool to query bank account and sync transaction data to pretix server.";
       days = mkOption {