diff --git a/tests/modmail/conftest.py b/tests/modmail/conftest.py
index ec3baa96..650621c9 100644
--- a/tests/modmail/conftest.py
+++ b/tests/modmail/conftest.py
@@ -8,6 +8,8 @@
 
 _ORIG_ENVIRON = None
 
+_modmail_env_prefix = "MODMAIL_"
+
 
 def pytest_report_header(config) -> str:
     """Pytest headers."""
@@ -26,17 +28,35 @@ def _get_env():
     return pathlib.Path(__file__).parent / "test.env"
 
 
+def _get_env_vars() -> dict:
+    result = {}
+    for key, value in os.environ.items():
+        # not using upper() since the config system is case sensitive
+        if key.startswith(_modmail_env_prefix):
+            result[key] = value
+    return result
+
+
 def pytest_configure():
     """Load the test specific environment file, exit if it does not exist."""
+    global _ORIG_ENVIRON
     env = _get_env()
     if not env.is_file():
         pytest.exit(f"Testing specific {env} does not exist. Cancelling test run.", 2)
-    os.environ.clear()
+    _ORIG_ENVIRON = _get_env_vars()
+    for key in _ORIG_ENVIRON:
+        del os.environ[key]
+
     dotenv.load_dotenv(_get_env(), override=True)
 
 
 def pytest_unconfigure():
     """Reset os.environ to the original environment before the run."""
-    if _ORIG_ENVIRON is not None:
-        os.environ.clear()
-        os.environ.update(**_ORIG_ENVIRON)
+    global _ORIG_ENVIRON
+    if _ORIG_ENVIRON is None:
+        return
+
+    for key in _get_env_vars():
+        del os.environ[key]
+    os.environ.update(**_ORIG_ENVIRON)
+    _ORIG_ENVIRON = None