diff --git a/src/common/gen/Configurator.py b/src/common/gen/Configurator.py
index eed443807..a6f89e842 100644
--- a/src/common/gen/Configurator.py
+++ b/src/common/gen/Configurator.py
@@ -49,7 +49,7 @@ def __init__(
         self.__compiled_regexes = {}
 
         # Pre-defined exclusion sets for config processing
-        self.__excluded_prefixes = ("_", "PYTHON", "KUBERNETES_", "SVC_", "LB_", "SUPERVISOR_")
+        self.__excluded_prefixes = ("PYTHON", "KUBERNETES_", "NOMAD_", "SVC_", "LB_", "SUPERVISOR_")
         self.__excluded_vars = frozenset(
             {
                 "DOCKER_HOST",
@@ -111,6 +111,21 @@ def __init__(
         else:
             self.__variables = variables
 
+        # Allow a leading underscore prefix on env var names so that domain names
+        # starting with a digit can be configured (bash forbids var names starting
+        # with a digit, e.g. 1nteresting.io).  Users write _1nteresting.io_USE_...
+        # and we strip the single leading underscore here before any other processing.
+        stripped: Dict[str, str] = {}
+        for k, v in self.__variables.items():
+            new_key = k.removeprefix("_")
+            if not new_key:
+                # Skip bare "_" or similar empty-after-strip keys
+                continue
+            if new_key in stripped:
+                self.__logger.warning(f"Variable collision after stripping leading underscore: both {k!r} and {new_key!r} exist, keeping last value")
+            stripped[new_key] = v
+        self.__variables = stripped
+
         self.__multisite = self.__variables.get("MULTISITE", "no") == "yes"
         self.__servers = self.__map_servers()